Organic semiconductor compositions

ABSTRACT

The present invention relates to organic semiconductor compositions and organic semiconductor layers and devices comprising such organic semiconductor compositions. The invention is also concerned with methods of preparing such organic semiconductor compositions and layers and uses thereof. The invention has application particularly in the field of displays such as organic field effect transistors (OFETS), integrated circuits, organic light emitting diodes (OLEDS), photodetectors, organic photovoltaic (OPV) cells, sensors, lasers, memory elements and logic circuits.

FIELD OF THE INVENTION

The present invention relates to organic semiconductor compositions andorganic semiconductor layers and devices comprising such organicsemiconductor compositions. The invention is also concerned with methodsof preparing such organic semiconductor compositions and layers and usesthereof. The invention has application particularly in the field ofdisplays such as organic field effect transistors (OFETs), integratedcircuits, organic light emitting diodes (OLEDs), photodetectors, organicphotovoltaic (OPV) cells, sensors, lasers, memory elements and logiccircuits.

BACKGROUND OF THE INVENTION

In recent years, there has been an increasing interest in organicsemiconducting materials as an alternative to the conventionalsilicon-based semiconductors. Organic semiconducting materials haveseveral advantages over those based on silicon, such as low cost andease of manufacturing as well as increased flexibility, mechanicalrobustness, good compatibility with a wide variety of flexiblesubstrates and light weight. They thus offer the possibility ofproducing more convenient and high performance electronic devices.

Polyacene compounds in particular have shown promise in this field oftechnology. WO 2005/055248 for example, discloses an organicsemiconducting layer formulation comprising an organic binder which hasa permittivity (E) at 1000 Hz of 3.3 or less, and a polyacene compound.However the method for preparing the OFETs described in WO 2005/055248in practice is limited and is only useful for producing top gate OFETs.A further disadvantage of WO 2005/055248 that is overcome by the presentinvention, is that it frequently uses undesirable chlorinated solvents.The highest performance semiconductor compositions disclosed in WO2005/055248 having mobilities ≧1.0 cm²V⁻¹ s⁻¹, incorporated1,2-dichlorobenzene as the solvent (page 54, Table 5 and examples 14, 21and 25). Moreover these solvents are not ones that would be industriallyuseful in a printing process and these are also damaging to theenvironment. Therefore it would be desirable to use more benign solventsfor the manufacture of these semiconductor compositions. Furthermore, itwas generally thought that only polymer binders with a permittivity ofless than 3.3 could be used since any polymers with a higherpermittivity resulted in a very significant reduction in mobility valuesof the OFET device.

This reduction in mobility value can further be seen in WO 2007/078993which discloses the use of 2,3,9,10-substituted pentacene compounds incombination with a polymer having a dielectric constant at 1000 Hz ofgreater than 3.3. These compositions are reported to exhibit mobilityvalues of between 10′ and 10′ cm²V⁻¹ s⁻¹ which are too low to beindustrially useful.

Therefore, the present invention seeks to provide organic semiconductorcompositions, which overcome the above-mentioned problems, by providingpolyacene compounds in combination with organic binders having anacceptable permittivity value, which exhibit high mobility values andwhich are soluble in a range of non-chlorinated solvents.

SUMMARY OF THE INVENTION

Polyacene Compounds Polyacene compounds according to the presentinvention are of Formula (1):

wherein each of R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹, R¹², R¹³and R¹⁴, which may be the same or different, independently representshydrogen; a branched or unbranched, substituted or unsubstituted C₁-C₄₀alkyl group; a branched or unbranched, substituted or unsubstitutedC₂-C₄₀ alkenyl group; a branched or unbranched, substituted orunsubstituted C₂-C₄₀ alkynyl group; an optionally substituted C₃-C₄₀cycloalkyl group; an optionally substituted C₆-C₄₀ aryl group; anoptionally substituted C₁-C₄₀ heterocyclic group; an optionallysubstituted C₁-C₄₀ heteroaryl group; an optionally substituted C₁-C₄₀alkoxy group; an optionally substituted C₆-C₄₀ aryloxy group; anoptionally substituted C₇-C₄₀ alkylaryloxy group; an optionallysubstituted C₂-C₄₀ alkoxycarbonyl group; an optionally substitutedC₇-C₄₀ aryloxycarbonyl group; a cyano group (—CN); a carbamoyl group(—C(═O)NR¹⁵R¹⁶); a carbonyl group (—C(═O)—R¹⁷); a carboxyl group(—CO₂R¹⁸) a cyanate group (—OCN); an isocyano group (—NC); an isocyanategroup (—NCO); a thiocyanate group (—SCN) or a thioisocyanate group(—NCS); an optionally substituted amino group; a hydroxy group; a nitrogroup; a CF₃ group; a halo group (Cl, Br, F, I); —SR¹⁹; —SO₃H; —SO₂R²⁰;—SF₅; an optionally substituted silyl group; a C₂-C₁₀ alkynyl groupsubstituted with a SiH₂R²² group, a C₂-C₁₀ alkynyl substituted with aSiHR²²R²³ group, or a C₂-C₁₀ alkynyl substituted with a SiR²²R²³R²⁴group;

wherein each of R¹⁵, R¹⁶, R¹⁸, R¹⁹ and R²⁰ independently represent H oroptionally substituted C₁-C₄₀ carbyl or hydrocarbyl group optionallycomprising one or more heteroatoms;

wherein R¹⁷ represents a halogen atom, H or optionally substitutedC₁-C₄₀ carbyl or C₁-C₄₀ hydrocarbyl group optionally comprising one ormore heteroatoms;

wherein, independently, each pair of R² and R³ and/or R⁹ and R¹⁰, may becross-bridged to form a C₄-C₄₀ saturated or unsaturated ring, whichsaturated or unsaturated ring may be intervened by an oxygen atom, asulphur atom or a group shown by formula —N(R²¹)— (wherein R²¹ is ahydrogen atom or an optionally substituted C₁-C₄₀ hydrocarbon group), ormay optionally be substituted; and wherein one or more of the carbonatoms of the polyacene skeleton may optionally be substituted by aheteroatom selected from N, P, As, O, S, Se and Te;

wherein R²², R²³ and R²⁴ are independently selected from the groupconsisting of hydrogen, a C₁-C₄₀ alkyl group which may optionally besubstituted for example with a halogen atom; a C₆-C₄₀ aryl group whichmay optionally be substituted for example with a halogen atom; a C₇-C₄₀arylalkyl group which may optionally be substituted for example with ahalogen atom; a C₁-C₄₀ alkoxy group which may optionally be substitutedfor example with a halogen atom; or a C₇-C₄₀ arylalkyloxy group whichmay optionally be substituted for example with a halogen atom;

wherein independently any two or more of the substituents R¹-R¹⁴ whichare located on adjacent ring positions of the polyacene may, together,optionally constitute a further C₄-C₄₀ saturated or unsaturated ringoptionally interrupted by O, S or —N(R²¹) where R²¹ is as defined above;or an aromatic ring system, fused to the polyacene; and

wherein k and l are independently 0, 1 or 2.

Preferably, k=l=0 or 1.

Preferably, k=1 and l=1.

In a preferred embodiment, at least one (and more preferably 2) ofgroups R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹, R¹², R¹³ and R¹⁴are tri-C₁₋₂₀ hydrocarbylsilyl C₁₋₄ alkynyl groups (i.e., C₁₋₂₀hydrocarbyl-SiR²²R²³R²⁴), wherein R²², R²³ and R²⁴ independentlyrepresent C₁-C₆ alkyl or C₂-C₆ alkenyl.

In a preferred embodiment, at least one (and more preferably 2) ofgroups R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹, R¹², R¹³ and R¹⁴are trihydrocarbylsilyl ethynyl groups (—C≡C—SiR²²R²³R²⁴), wherein R²²,R²³ and R²⁴ independently represent C₁-C₆ alkyl or C₂-C₆ alkenyl. In amore preferred embodiment, R²², R²³ and R²⁴ are independently selectedfrom the group consisting of methyl, ethyl, propyl, isopropyl, n-butyl,isobutyl, t-butyl, 1-propenyl and 2-propenyl.

In a preferred embodiment, R⁶ and R¹³ are trialkylsilyl ethynyl groups(—C≡C—SiR²²R²³R²⁴), wherein R²², R²³ and R²⁴ independently representC₁-C₆ alkyl or C₂-C₆ alkenyl. In a more preferred embodiment, R²², R²³and R²⁴ are independently selected from the group consisting of methyl,ethyl, propyl, isopropyl, n-butyl, isobutyl, t-butyl 1-propenyl and2-propenyl.

In yet another preferred embodiment, when k=l=1; R¹, R², R³, R⁴, R⁸, R⁹,R¹⁰ and R¹¹ independently represent H, C₁-C₆ alkyl or C₁-C₆ alkoxy. Morepreferably, R¹, R⁴, R⁸ and R¹¹ are the same and represent H, C₁-C₆ alkylor C₁-C₆ alkoxy. In an even more preferred embodiment, R¹, R², R³, R⁴,R⁸, R⁹, R¹⁰ and R¹¹ are the same or different and are selected from thegroup consisting of hydrogen, methyl, ethyl, propyl, n-butyl, isobutyl,t-butyl, methoxy, ethoxy, propyloxy and butyloxy.

In yet another embodiment, when k=l=0 or 1, independently each pair ofR² and R³ and/or R⁹ and R¹⁰, are cross-bridged to form a C₄-C₁₀saturated or unsaturated ring, which saturated or unsaturated ring maybe intervened by an oxygen atom, a sulphur atom or a group shown byformula —N(R²¹)— (wherein R²¹ is a hydrogen atom or a cyclic, straightchain or branched C₁-C₁₀ alkyl group); and wherein one or more of thecarbon atoms of the polyacene skeleton may optionally be substituted bya heteroatom selected from N, P, As, O, S, Se and Te.

Preferably, R⁵, R⁷, R¹² and R¹⁴ are hydrogen.

Preferably, R²², R²³ and R²⁴ are independently selected from the groupconsisting hydrogen, a C₁-C₁₀ alkyl group (preferably C₁-C₄-alkyl andmost preferably methyl, ethyl, n-propyl or isopropyl) which mayoptionally be substituted for example with a halogen atom; a C₆-C₁₂ arylgroup (preferably phenyl) which may optionally be substituted forexample with a halogen atom; a C₇-C₁₆ arylalkyl group which mayoptionally be substituted for example with a halogen atom; a C₁-C₁₀alkoxy group which may optionally be substituted for example with ahalogen atom; or a C₇-C₁₆ arylalkyloxy group which may optionally besubstituted for example with a halogen atom.

R²², R²³ and R²⁴ are preferably independently selected from the groupconsisting optionally substituted C₁₋₁₀ alkyl group and optionallysubstituted C₂₋₁₀ alkenyl, more preferably C₁-C₆ alkyl or C₂-C₆ alkenyl.A preferred alkyl group in this case is isopropyl.

Examples of the silyl group —SiR²²R²³R²⁴ include, without limitation,trimethylsilyl, triethylsilyl, tripropylsilyl, dimethylethylsilyl,diethylmethylsilyl, dimethylpropylsilyl, dimethylisopropylsilyl,dipropylmethylsilyl, diisopropylmethylsilyl, dipropylethylsilyl,diisopropylethylsilyl, diethylisopropylsilyl, triisopropylsilyl,trimethoxysilyl, triethoxysilyl, triphenylsilyl, diphenylisopropylsilyl,diisopropylphenylsilyl, diphenylethylsilyl, diethylphenylsilyl,diphenylmethylsilyl, triphenoxysilyl, dimethylmethoxysilyl,dimethylphenoxysilyl, methylmethoxyphenyl, etc. For each example in theforegoing list, the alkyl, aryl or alkoxy group may optionally besubstituted.

In a preferred embodiment of the first aspect of the invention,polyacene compounds according to the present invention are of Formula(1a):

wherein each of R⁵, R⁷, R¹² and R¹⁴ are hydrogen;

R⁶ and R¹³ are trialkylsilyl ethynyl groups (—C≡C—SiR²²R²³R²⁴), whereinR²², R²³ and R²⁴ independently represent C₁-C₄ alkyl or C₂-C₄ alkenyl;

R¹, R², R³, R⁴, R⁸, R⁹, R¹⁰ and R¹¹ are independently selected from thegroup consisting of hydrogen; a branched or unbranched, unsubstitutedC₁-C₄ alkyl group; C₁-C₆ alkoxy group and C₆-C₁₂ aryloxy group;

or wherein independently each pair of R² and R³ and/or R⁹ and R¹⁰, maybe cross-bridged to form a C₄-C₁₀ saturated or unsaturated ring, whichsaturated or unsaturated ring may be intervened by an oxygen atom, asulphur atom or a group shown by formula —N(R²¹)— (wherein R²¹ is ahydrogen atom or an optionally substituted C₁-C₆ alkyl group);

wherein k and l are independently 0, or 1, preferably both k and l are1.

In compounds of Formula (1a), wherein k and l are both 1; R⁶ and R¹³ aretrialkylsilyl ethynyl groups (—C≡C—SiR²²R²³R²⁴), wherein R²², R²³ andR²⁴ are preferably selected from ethyl, n-propyl, isopropyl, 1-propenylor 2-propenyl; R¹, R², R³, R⁴, R⁸, R⁹, R¹⁰ and R¹¹ are independentlyselected from the group consisting of hydrogen, methyl, ethyl andmethoxy.

In compounds of Formula (1a), wherein k and l are both 0; R⁶ and R¹³ arepreferably trialkylsilyl ethynyl groups (—C≡C—SiR²²R²³R²⁴), wherein R²²,R²³ and R²⁴ are preferably selected from ethyl, n-propyl, isopropyl,1-propenyl or 2-propenyl; R¹, R⁴, R⁸ and R¹¹ are preferably hydrogen;and R² and R³ together, and R⁹ and R¹⁰ together preferably form5-membered heterocyclic rings containing 1 or 2 nitrogen atoms, 1 or 2sulphur atoms or 1 or 2 oxygen atoms.

Especially preferred polyacene compounds according to the presentinvention are those of Formulae (2) and (3):

wherein R¹, R⁴, R⁸ and R¹¹ are independently selected from the groupconsisting of H, C₁-C₆ alkyl and C₁-C₆ alkoxy. Preferably R¹, R⁴, R⁸ andR¹¹ are the same or different and are independently selected from thegroup consisting of hydrogen, methyl, ethyl, propyl, n-butyl, isobutyl,t-butyl, methoxy, ethoxy, propyloxy and butyloxy, more preferablyhydrogen, methyl, propyl and methoxy.

In compounds of Formula (2), R², R³, R⁹ and R¹⁰ are independentlyselected from the group consisting of H, C₁-C₆ alkyl and C₁-C₆ alkoxy,or each pair of R² and R³ and/or R⁹ and R¹⁰, are cross-bridged to form aC₄-C₁₀ saturated or unsaturated ring, which saturated or unsaturatedring may be intervened by an oxygen atom, a sulphur atom or a groupshown by formula —N(R²¹)— (wherein R²¹ is a hydrogen atom or a cyclic,straight chain or branched C₁-C₁₀ alkyl group); and wherein one or moreof the carbon atoms of the polyacene skeleton may optionally besubstituted by a heteroatom selected from N, P, As, O, S, Se and Te. Ina preferred embodiment, R², R³, R⁹ and R¹⁰ are the same or different andare independently selected from the group consisting of hydrogen,methyl, ethyl, propyl, n-butyl, isobutyl, t-butyl, methoxy, ethoxy,propyloxy and butyloxy, more preferably hydrogen, methyl, ethyl, propyland methoxy;

In compounds of Formulae (2) and (3), R²⁵, R²⁶ and R²⁷ are independentlyselected from the group consisting of C₁-C₆ alkyl and C₂-C₆ alkenyl,preferably R²², R²³ and R²⁴ are independently selected from the groupconsisting of methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl,t-butyl, 1-propenyl and 2-propenyl, more preferably ethyl, n-propyl andisopropyl.

In compounds of Formula (3), R²⁸ and R²⁹ are independently selected fromthe group consisting of hydrogen, halogen, —CN, optionally fluorinatedor perfluorinated, straight chain or branched C₁-C₂₀ alkyl, fluorinatedor perfluorinated, straight chain or branched C₁-C₂₀ alkoxy, fluorinatedor perfluorinated C₆-C₃₀ aryl and CO₂R³⁰, wherein R³⁰ is H, fluorinatedor perfluorinated, straight chain or branched C₁-C₂₀ alkyl, andfluorinated or perfluorinated C₆-C₃₀ aryl. Preferably R²⁸ and R²⁹ areindependently selected from the group consisting of fluorinated orperfluorinated, straight chain or branched C₁-C₈ alkyl, fluorinated orperfluorinated, straight chain or branched C₁-C₈ alkoxy and C₆F₅.

In compounds of Formula (3), Y¹, Y², Y³ and Y⁴ are preferablyindependently selected from the group consisting of —CH═, ═CH—, O, S, Seor NR³¹ (wherein R³¹ is a hydrogen atom or a cyclic, straight chain orbranched C₁-C₁₀ alkyl group).

In yet another preferred embodiment, the polyacene compounds of thepresent invention are those of Formulae (4) and (5):

wherein R²⁵, R²⁶ and R²⁷ are independently selected from the groupconsisting of methyl, ethyl and isopropyl;

wherein R¹, R², R³, R⁴, R⁸, R⁹, R¹⁰ and R¹¹ are independently selectedfrom the group consisting of C₁-C₆ alkyl, C₁-C₆ alkoxy and C₆-C₂₀aryloxy. Preferably R¹, R², R³, R⁴, R⁸, R⁹, R¹⁰ and R¹¹ areindependently selected from the group consisting of methyl, ethyl,propyl, n-butyl, isobutyl, t-butyl, methoxy, ethoxy, propyloxy andbutyloxy groups.

In some preferred embodiments, when R¹, R⁴, R⁸ and R¹¹ are the same andare methyl or methoxy groups, R²⁵, R²⁶ and R²⁷ are the same and areethyl or isopropyl groups. In a preferred embodiment, when R¹, R⁴, R⁸and R¹¹ are methyl groups, R²⁵, R²⁶ and R²⁷ are ethyl groups. In yetanother a preferred embodiment, when R¹, R⁴, R⁸ and R¹¹ are methylgroups, R²⁵, R²⁶ and R²⁷ are isopropyl groups. In a further preferredembodiment, when R¹, R⁴, R⁸ and R¹¹ are methoxy groups, R²⁵, R²⁶ and R²⁷are ethyl groups. In yet another preferred embodiment, when R¹, R⁴, R⁸and R¹¹ are methoxy groups, R²⁵, R²⁶ and R²⁷ are isopropyl groups.

In some preferred embodiments when R², R³, R⁹ and R¹⁰ are the same andare methyl or methoxy groups, R²⁵, R²⁶ and R²⁷ are the same and areethyl or isopropyl groups. In a preferred embodiment, when R², R³, R⁹and R¹⁰ are methyl groups, R²⁵, R²⁶ and R²⁷ are ethyl groups. In yetanother a preferred embodiment, when R², R³, R⁹ and R¹⁰ are methylgroups, R²⁵, R²⁶ and R²⁷ are isopropyl groups. In a further preferredembodiment, when R², R³, R⁹ and R¹⁰ are methoxy groups, R²⁵, R²⁶ and R²⁷are ethyl groups. In yet another preferred embodiment, when R², R³, R⁹and R¹⁰ are methoxy groups, R²⁵, R²⁶ and R²⁷ are isopropyl groups.

In an even more preferred embodiment of the present invention, thepolyacene compound is selected from the following compounds (A) to (F):

The “R” substituents (that is R¹, R², etc) denote the substituents atthe positions of pentacene according to conventional nomenclature:

Polyacene compounds according to the present invention may besynthesised by any known method within the common general knowledge of aperson skilled in the art. In a preferred embodiment, methods disclosedin US 2003/0116755 A, U.S. Pat. No. 3,557,233, U.S. Pat. No. 6,690,029WO 2007/078993, WO 2008/128618 and Organic Letters, 2004, Volume 6,number 10, pages 1609-1612 can be employed for the synthesis ofpolyacene compounds according to the present invention.

Preferably, the polyacene compounds according to the present inventionhave an electrical conductivity in the range of 10³ to 10⁻⁸ siemens percentimetre, preferably between 500 to 10⁻⁷, more preferably between 300to 10⁻⁶, more preferably between 250 to 10⁻⁵, more preferably between 10to 10⁻⁵ siemens per centimetre, more preferably greater than 10⁻⁴ or10⁻³ siemens per centimetre.

Organic Binders

Organic binders according to the present invention are semiconductingbinders having a permittivity at 1000 Hz of between 3.4 and 8. In apreferred embodiment, the organic binders have a permittivity at 1000 Hzof between 3.4 and 6.0, and more preferably between 3.4 and 4.5. Thepermittivity of the organic binders can be measured using any standardmethod known to those skilled in the art. In a preferred embodiment, thepermittivity is determined by the method disclosed in WO 2004/102690 orby using the method disclosed herein, preferably by using the methoddisclosed herein.

In a preferred embodiment, the organic binders according to the presentinvention are those comprising a unit of Formula (6):

wherein Ar₁, Ar₂ and Ar₃, which may be the same or different, eachrepresent, independently if in different repeat units, an optionallysubstituted C₆₋₄₀ aromatic group (mononuclear or polynuclear), whereinat least one of Ar₁, Ar₂ and Ar₃ is substituted with at least one polaror more polarising group, and n=1 to 20, preferably 1 to 10 and morepreferably 1 to 5. Preferably, at least one of Ar₁, Ar₂ and Ar₃ issubstituted with 1, 2, 3, or 4, more preferably 1, 2 or 3, morepreferably 1 or 2, preferably 1 polar or more polarising group(s).

In a preferred embodiment, the one or more polar or polarising group(s)is independently selected from the group consisting of nitro group,nitrile group, C₁₋₄₀ alkyl group substituted with a nitro group, anitrile group, a cyanate group, an isocyanate group, a thiocyanate groupor a thioisocyanate group; C₁₋₄₀ alkoxy group optionally substitutedwith a nitro group, a nitrile group, a cyanate group, an isocyanategroup, a thiocyanate group or a thioisocyanate group; C₁₋₄₀ carboxylicacid group optionally substituted with a nitro group, a nitrile group, acyanate group, an isocyanate group, a thiocyanate group or athioisocyanate group; C₂₋₄₀ carboxylic acid ester optionally substitutedwith a nitro group, a nitrile group, a cyanate group, an isocyanategroup, a thiocyanate group or a thioisocyanate group; sulfonic acidoptionally substituted with a nitro group, a nitrile group, a cyanategroup, an isocyanate group, a thiocyanate group or a thioisocyanategroup; sulfonic acid ester optionally substituted with a nitro group, anitrile group, a cyanate group, an isocyanate group, a thiocyanate groupor a thioisocyanate group; cyanate group, isocyanate group, thiocyanategroup, thioisocyanate group; and an amino group optionally substitutedwith a nitro group, a nitrile group, a cyanate group, an isocyanategroup, a thiocyanate group or a thioisocyanate group; and combinationsthereof.

In a more preferred embodiment, the one or more polar or polarisinggroup(s) is independently selected from the group consisting of nitrogroup, nitrile group, C₁₋₁₀ alkyl group substituted with a nitrilegroup, a cyanate group, or an isocyanate group; C₁₋₂₀ alkoxy group,C₁₋₂₀ carboxylic acid group, C₂₋₂₀ carboxylic acid ester; sulfonic acidester; cyanate group, isocyanate group, thiocyanate group,thioisocyanate group, and an amino group; and combinations thereof.

More preferably the polar or polarizing group is selected from the groupconsisting of C₁₋₄ cyanoalkyl group, C₁₋₁₀ alkoxy group, nitrile groupand combinations thereof.

More preferably the polar or polarizing group is selected from the groupconsisting of cyanomethyl, cyanoethyl, cyanopropyl, cyanobutyl, methoxy,ethoxy, propoxy, butoxy, nitrile, NH₂ and combinations thereof.Preferably at least one of Ar₁, Ar₂ and Ar₃ is substituted with 1 or 2polar or more polarising group, which may be the same or different.

In the context of Ar₁, Ar₂ and Ar₃, a mononuclear aromatic group hasonly one aromatic ring, for example phenyl or phenylene. A polynucleararomatic group has two or more aromatic rings which may be fused (forexample napthyl or naphthylene), individually covalently linked (forexample biphenyl) and/or a combination of both fused and individuallylinked aromatic rings. Preferably each Ar₁, Ar₂ and Ar₃ is an aromaticgroup which is substantially conjugated over substantially the wholegroup.

Preferably, Ar₁, Ar₂ and Ar₃, are independently selected from the groupconsisting of C₆₋₂₀ aryl, C₇₋₂₀ aralkyl and C₇₋₂₀ alkaryl, any of whichmay be substituted with 1, 2, or 3 groups independently selected fromC₁₋₄ alkoxy, C₁₋₄ cyanoalkyl, CN and mixtures thereof, and n=1 to 10.

Preferably, Ar₁, Ar₂ and Ar₃, are independently selected from the groupconsisting of C₆₋₁₀ aryl, C₇₋₁₂ aralkyl and C₇₋₁₂ alkaryl, any of whichmay be substituted with 1, 2, or 3 groups independently selected fromC₁₋₂ alkoxy, C₁₋₃ cyanoalkyl, CN and mixtures thereof, and n=1 to 10.

Preferably, Ar₁, Ar₂ and Ar₃, are independently selected from the groupconsisting of phenyl, benzyl, tolyl and naphthyl, any of which may besubstituted with 1, 2 or 3 groups independently selected from methoxy,ethoxy, cyanomethyl, cyanoethyl, CN and mixtures thereof, and n=1 to 10.

Preferably, Ar₁, Ar₂ and Ar₃, are all phenyl which may be independentlysubstituted with 1, 2 or 3 groups selected from methoxy, ethoxy,cyanomethyl, cyanoethyl, CN and mixtures thereof, and n=1 to 10.

Preferably, Ar₁, Ar₂ and Ar₃, are all phenyl which may be independentlysubstituted with 1 or 2 groups selected from methoxy, cyanomethyl, CNand mixtures thereof, and n=1 to 10.

In a further preferred embodiment, the organic binder may be a random orblock copolymer of different triarylamine monomers. In such a case, anycompound as defined by Formula (6) may be combined with a differentcompound of Formula (6) to provide the random or block copolymeraccording to the present invention. For example, the organic binder maybe a copolymer of a nitro-substituted triarylamine with a 2,4-dimethylsubstituted triarylamine. The ratio of the monomers in the polymers canbe altered to allow for adjustment of the permittivity relative to ahomopolymer. Furthermore, preferably the organic binder (6) may be mixedwith organic binders which do not meet the definition of (6), as long asthe average permittivity of the compositions is between 3.4 and 8.0.

In an even more preferred embodiment of the present invention, theorganic binder comprises at least one unit having the structures (G) to(J):

The organic binders according to the present invention preferably have anumber average molecular weight (Mn) of between 300 and 20,000, morepreferably between 1600 and 5000, more preferably between 500 and 4000,even more preferably between 450 and 3000 and yet more preferablybetween 500 and 2000.

Preferably, the organic semiconductor compositions according to thepresent invention contain less than 10% by weight, more preferably lessthan 5% by weight, more preferably less than 1% of organic binders whichhave a permittivity at 1000 Hz of less than 3.4. In a preferredembodiment, the permittivity is determined by the method disclosed in WO2004/102690 or by using the method disclosed herein, preferably by usingthe method disclosed herein.

The organic binders according to the present invention preferably have acharge mobility value greater than μ=1×10⁻⁷ cm²V⁻¹ s⁻¹, and morepreferably greater than μ=1×10⁻⁶ cm²V⁻¹ s⁻¹

Organic Semiconductor Compositions

An organic semiconductor composition according to the first aspect ofthe present invention comprises a polyacene compound and an organicbinder, wherein the organic binder has a permittivity at 1000 Hz ofbetween 3.4 and 6.5.

The organic semiconductor composition according to the present inventioncan comprise any combination of polyacene compound and organic bindersherein disclosed. In a preferred embodiment, an organic semiconductorcomposition may comprise a polyacene compound according to Formula (1)in combination with an organic binder, wherein the organic binder has apermittivity at 1000 Hz of between 3.4 and 8, preferably between 3.4 and6.5 and more preferably between 3.4 and 4.5.

In a particularly preferred embodiment, a polyacene compound accordingto any of Formulae (2) to (5) may be used in combination with an organicbinder, wherein the organic binder has a permittivity at 1000 Hz ofbetween 3.4 and 8.0, preferably between 3.4 and 6.0 and more preferablybetween 3.4 and 4.5.

In yet another preferred embodiment, any of polyacene compounds (A) to(F) may be used in combination with an organic binder, wherein theorganic binder has a permittivity at 1000 Hz of between 3.4 and 8.0,preferably between 3.4 and 6.5 and more preferably between 3.4 and 4.5.

In another preferred embodiment, an organic semiconductor compositionmay comprise a polyacene compound according to Formula (1) incombination with an organic binder comprising a unit of Formula (6).Preferably, the organic binder comprising a unit of Formula (6) has apermittivity at 1000 Hz of between 3.4 and 8.0, preferably between 3.4and 6.5 and more preferably between 3.4 and 4.5.

In yet a further preferred embodiment, an organic semiconductorcomposition may comprise a polyacene compound according to any ofFormulae (2) to (5) in combination with an organic binder comprising aunit of Formula (6).

In yet another preferred embodiment, an organic semiconductorcomposition may comprise any of polyacene compounds (A) to (F) incombination with an organic binder comprising a unit of Formula (6).

A further preferred organic semiconductor composition may comprise apolyacene compound according to any of Formulae (1) to (5) incombination with any of the organic binders comprising at least one unithaving the structures (G) to (J).

The concentration of the polyacene compound, the organic binder andsolvent present in the composition will vary depending on the preferredsolution coating method, for example ink jet printing compositionsrequire low viscosity, low solids loading compositions, whilst screenprinting processes require high viscosity, high solids loadingcompositions. Following deposition of the semiconductor-bindercomposition, the solvent is evaporated to afford the semiconductor layerhaving 1-99.9% by weight of the binder and 0.1 to 99% by weight of thepolyacene semiconductor (in the printed or dried state) based on a totalweight of the composition; preferably the semiconductor layer having 25to 75% by weight of the binder and 25 to 75% by weight of the polyacenesemiconductor.

In the composition prior to deposition, one or more of theabove-described polyacene compounds are preferably present at aconcentration of at least 0.1 wt % based on a total weight of thecomposition. The upper limit of the concentration of the polyacenecompound in the composition is often near the solubility limit of thatcompound in the particular solvent at the temperature of the compositionduring its application to a substrate such as in the fabrication of anelectronic device. Typical compositions of the present inventioncomprise one of the polyacene compounds at a concentration ranging fromabout 0.1 wt % to about 20.0 wt % based on a total weight of thecomposition, more typically, from about 0.5 wt % to about 10.0 wt %,more typically 0.5 to 5.0 wt %.

In the composition prior to deposition, one or more of theabove-described organic binders are preferably present at aconcentration of at least 0.1 wt % based on a total weight of thecomposition. Preferred compositions of the present invention compriseone of the organic binders at a concentration ranging from about 0.1 wt% to about 20.0 wt %, more typically, from about 0.5 wt % to about 10.0wt %, more typically 0.5 to 5.0 wt %.

In the printed or dried composition, one or more of the above-describedpolyacene compounds are preferably present at a concentration of atleast 10 wt % based on a total weight of the composition, preferablybetween 10 and 90 wt %, more preferably between 20 and 80 wt %, morepreferably between 30 and 70 wt %, more preferably between 40 and 60 wt%.

In the printed or dried composition, one or more of the above-describedorganic binders are preferably present at a concentration of at least 10wt % based on a total weight of the composition, preferably between 10and 90 wt %, more preferably between 20 and 80 wt %, more preferablybetween 30 and 70 wt %, more preferably between 40 and 60 wt %.

In a preferred embodiment, one or more solvents may be present in theorganic semiconductor compositions. Suitable solvents include, but arenot limited to, organic solvents such as ketones, aromatic hydrocarbons,fluorinated solvents, and the like. Preferably the solvent is selectedfrom the group of aromatic hydrocarbon solvents including benzene,toluene, xylene, ethylbenzene, butylbenzene, anisole, bromomesityleneand tetrahydronapthalene or from tetrahydrofuran, isophorone,butylcyclohexane and cyclohexanone. Solvent blends may also be utilised.Suitable solvent blends include, but are not limited to compositions ofthe above solvents in conjunction with solvents such asdimethylformamide, dimethylacetamide, dimethylsulfoxide, methyl ethylketone, dichloromethane, dichlorobenzene, furfuryl alcohol,dimethoxyethane and ethyl acetate. Such compositions (prior todeposition) preferably contain a suitable solvent in an amount ofgreater than 50 wt % based on a total weight of the composition,preferably between 60 and 95 wt % based on a total weight of thecomposition.

In yet another preferred embodiment, one or more additional compositioncomponents may be present in the organic semiconductor composition.Suitable additional composition components include, but are not limitedto, a polymer additive, a rheological modifier, a surfactant, anothersemiconductor that is a complementary hole transfer partner for thepolyacene compound or a combination thereof. In some exemplaryembodiments, the compositions comprise a polymer additive selected fromthe group consisting of polystyrene, poly(alpha-methylstyrene),poly(pentafluorostyrene), poly(methyl methacrylate), poly(4-cyanomethylstyrene), poly(4-vinylphenol), or any other suitable polymer disclosedin U.S. Patent Application Publication No. 2004/0222412 A1 or U.S.Patent Application Publication No. 2007/0146426 A1. In some desiredembodiments, the polymer additive comprises polystyrene,poly(alpha-methylstyrene), poly(pentafluorostyrene) or poly(methylmethacrylate). In some exemplary embodiments, the compositions comprisea surfactant selected from fluorinated surfactants or fluorosurfactants.When present, each additional composition component is independentlypresent in an amount of greater than 0 to about 50 wt % based on a totalweight of the composition. Preferably, each additional compositioncomponent is independently present in an amount ranging from about0.0001 to about 10.0 wt % based on a total weight of the composition.For example, when a polymer is present in the composition, the polymeradditive is typically present in an amount of greater than 0 to about5.0 wt %, preferably from about 0.5 to about 3.0 wt % based on a totalweight of the composition. For example, when a surfactant is present inthe composition, the surfactant is preferably present in an amount ofgreater than 0 to about 1.0 wt %, more typically, from about 0.001 toabout 0.5 wt % based on a total weight of the composition.

The organic semiconductor composition according to the present inventionpreferably has a charge mobility value of at least 0.5 cm²V⁻¹ s⁻¹,preferably between 0.5 and 8.0 cm²V⁻¹ s⁻¹, more preferably between 0.5and 6.0 cm²V⁻¹ s⁻¹, more preferably between 0.8 and 5.0 cm²V⁻¹ s⁻¹, morepreferably between 1 and 5.0 cm²V⁻¹ s⁻¹, more preferably between 1.5 and5.0 cm²V⁻¹ s⁻¹, more preferably between 2 and 5.0 cm²V⁻¹ s⁻¹. The chargemobility value of the semiconductor composition can be measured usingany standard method known to those skilled in the art, such astechniques disclosed in J. Appl. Phys., 1994, Volume 75, page 7954 andWO 2005/055248, preferably by those described in WO 2005/055248.

The organic semiconductor composition according to the present inventionmay be prepared by any known method within the common general knowledgeof a person skilled in the art. In a preferred embodiment, the organicsemiconductor composition is prepared by the method disclosed in WO2005/055248 or by using the method disclosed herein, preferably by usingthe method disclosed herein.

Preferably, organic semiconductor composition according to the presentinvention are semiconducting compositions having a permittivity at 1000Hz of between 3.4 and 8. In a preferred embodiment, the compositionshave a permittivity at 1000 Hz of between 4.0 and 7, more preferablybetween 4.0 and 6.5, more preferably between 4.0 and 6 and even morepreferably between 3.4 and 4.5.

Preferably, the organic semiconductor composition according to thepresent invention has an electrical conductivity in the range of 10³ to10⁻⁸ siemens per centimetre, preferably between 500 to 10⁻⁷, morepreferably between 300 to 10⁻⁶, more preferably between 250 to 10⁻⁵,more preferably between 10 to 10⁻⁵ siemens per centimetre, morepreferably greater than 10⁻⁴ or 10⁻³ siemens per centimetre.

Organic Semiconductor Layers

The organic semiconductor compositions according to the presentinvention may be deposited onto a variety of substrates, to form organicsemiconductor layers.

The organic semiconductor layer according to the present invention maybe prepared using a method comprising the steps of:

-   -   (i) Mixing the organic semiconductor composition according to        the present invention with a solvent to form a semiconductor        layer formulation;    -   (ii) Depositing said formulation onto a substrate; and    -   (iii) Optionally removing the solvent to form an organic        semiconductor layer.

Useful substrate materials include, but are not limited to, polymericfilms such as polyamides, polycarbonates, polyimides, polyketones,polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), andinorganic substrates such as silica, alumina, silicon wafers and glass.The surface of a given substrate may be treated, e.g. by reaction ofchemical functionality inherent to the surface with chemical reagentssuch as silanes or exposure of the surface to plasma, in order to alterthe surface characteristics.

Prior to depositing the organic semiconductor composition onto thesubstrate, the composition may be combined with one or more solvents inorder to facilitate the deposition step. Suitable solvents include anysolvent which is able to dissolve both the organic binder and thepolyacene compound, and which upon evaporation from the solution blend,give a coherent, defect-free layer. Suitable solvents for the organicbinder and/or polyacene compound can be determined by preparing acontour diagram for the material as described in ASTM Method D 3132 atthe concentration at which the mixture will be employed. The material isadded to a wide variety of solvents as described in the ASTM method.

Suitable solvents include, but are not limited to, tetrahydrofuran,anisole, morpholine, toluene, o-xylene, m-xylene, p-xylene, 1,4-dioxane,acetone, methylethylketone, ethyl acetate, n-butyl acetate,dimethylformamide, dimethylacetamide, dimethylsulfoxide, tetralin,decalin and/or mixtures thereof. Preferably, no chlorinated solvents areused.

The proportions of organic binder to polyacene compound in thesemiconductor layer formulation according to the present invention aretypically 20:1 to 1:20 by weight, preferably 10:1 to 1:10, morepreferably 5:1 to 1:5, still more preferably 3:1 to 1:3, furtherpreferably 2:1 to 1:2 and especially 1:1.

In accordance with the present invention it has further been found thatthe level of the solids content in the organic semiconducting layerformulation is also a factor in achieving improved mobility values forelectronic devices such as OFETs. The solids content of the formulationis commonly expressed as follows:

${{Solids}\mspace{14mu} {content}\mspace{14mu} (\%)} = {\frac{a + b}{a + b + c} \times 100}$

wherein: a=mass of polyacene, b=mass of binder and c=mass of solvent.

The solids content of the formulation is preferably 0.1 to 10% byweight, more preferably 0.5 to 5% by weight.

Suitable conventional deposition methods include, but are not limitedto, spin coating, knife-coating, roll-to-roll web-coating, and dipcoating, as well as printing processes such as ink-jet printing, screenprinting, and offset lithography. In one desired embodiment, theresulting composition is a printable composition, even more desirably,an ink jet printable composition.

Once the composition is deposited onto a substrate surface, the solventmay be removed to form an organic semiconductor layer. Any suitablemethod may be used to remove the solvent. For example, the solvent maybe removed by evaporation or drying. Typically, at least about 80percent of the solvent is removed to form the semiconductor layer. Forexample, at least about 85 weight percent, at least about 90 weightpercent, at least about 92 weight percent, at least about 95 weightpercent, at least about 97 weight percent, at least about 98 weightpercent, at least about 99 weight percent, or at least about 99.5 weightpercent of the solvent is removed.

The solvent often can be evaporated at any suitable temperature. In somemethods, the solvent mixture is evaporated at ambient temperature. Inother methods, the solvent is evaporated at a temperature higher orlower than ambient temperature. For example, a platen supporting thesubstrate can be heated or cooled to a temperature higher or lower thanambient temperature. In still other preferred methods, some or most ofthe solvent can be evaporated at ambient temperature, and any remainingsolvent can be evaporated at a temperature higher than ambienttemperature. In methods where the solvent evaporates at a temperaturehigher than ambient temperature, the evaporation can be carried outunder an inert atmosphere, such as a nitrogen atmosphere.

Alternatively, the solvent can be removed by application of reducedpressure (i.e., at a pressure that is less than atmospheric pressure)such as through the use of a vacuum. During application of reducedpressure, the solvent can be removed at any suitable temperature such asthose described above.

The rate of removal of the solvent can affect the resultingsemiconductor layer. For example, if the removal process is too rapid,poor pi-pi crystal stacking of the semiconductor molecules can occurduring crystallisation. Poor packing of the semiconductor molecules canbe detrimental to the electrical performance of the semiconductor layer.The solvent can evaporate entirely on its own in an uncontrolled fashion(i.e. no time constraints), or the conditions can be controlled in orderto control the rate of evaporation. In order to minimise poor moleculepacking, the solvent can be evaporated while slowing the evaporationrate by covering the deposited layer. Such conditions can lead to asemiconductor layer having a relatively high crystallinity.

After removal of a desired amount of solvent to form the semiconductorlayer, the semiconductor layer can be annealed by exposure to heat orsolvent vapours, i.e., by thermal annealing or solvent annealing.

The organic semiconductor layer according to the present inventionpreferably has a charge mobility value of at least 0.5 cm²V⁻¹ s⁻¹,preferably between 0.5 and 8.0 cm²V⁻¹ s⁻¹, more preferably between 0.5and 6.0 cm²V⁻¹ s⁻¹, more preferably between 0.8 and 5.0 cm²V⁻¹ s⁻¹, morepreferably between 1 and 5.0 cm²V⁻¹ s⁻¹, more preferably between 1.5 and5.0 cm²V⁻¹ s⁻¹, more preferably between 2 and 5.0 cm²V⁻¹ s⁻¹. The chargemobility value of the semiconductor layer can be measured using anystandard method known to those skilled in the art, such as techniquesdisclosed in J. Appl. Phys., 1994, Volume 75, page 7954 and WO2005/055248, preferably by those described in WO 2005/055248.

Preferably, the organic semiconductor layer(s) of the present inventionare semiconducting layers having a permittivity at 1000 Hz of between3.4 and 8. In a preferred embodiment, the layer(s) have a permittivityat 1000 Hz of between 4.0 and 7, more preferably between 4.0 and 6.5,and even more preferably between 3.4 and 4.5.

Preferably, the organic semiconductor layer(s) according to the presentinvention has an electrical conductivity in the range of 10³ to 10⁻⁸siemens per centimetre, preferably between 500 to 10⁻⁷, more preferablybetween 300 to 10⁻⁶, more preferably between 250 to 10⁻⁵, morepreferably between 10 to 10⁻⁵ siemens per centimetre, more preferablygreater than 10⁻⁴ or 10⁻³ siemens per centimetre.

Electronic Devices

The invention additionally provides an electronic device comprising theorganic semiconductor composition according to the present invention.The composition may be used, for example, in the form of asemiconducting layer or film. Additionally, the invention preferablyprovides an electronic device comprising the organic semiconductor layeraccording to the present invention.

The thickness of the layer or film may be between 0.05 and 20 microns,preferably between 0.05 and 10 microns, between 0.05 and 5 microns andbetween 0.1 and 2 microns.

The electronic device may include, without limitation, organic fieldeffect transistors (OFETS), organic light emitting diodes (OLEDS),photodetectors, organic photovoltaic (OPV) cells, sensors, lasers,memory elements and logic circuits.

Exemplary electronic devices of the present invention may be fabricatedby solution deposition of the above-described organic semiconductorcomposition onto a substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a representation of top contact/bottom gate

FIG. 2 is a representation of bottom contact/bottom gate

FIG. 3 is a representation of top contact/top gate

FIG. 4 is a representation of bottom contact/top gate

Labels—A: Substrate; B: Gate electrode; C: Dielectric layer; D:Semiconductor layer; E: Source electrode; F: Gate electrode

DETAILED DESCRIPTION OF THE INVENTION General

The term “about” in relation to a numerical value x means, for example,x+10%.

The word “substantially” does not exclude “completely” e.g. acomposition which is “substantially free” from Y may be completely freefrom Y. Where necessary, the word “substantially” may be omitted fromthe definition of the invention.

“Molecular weight” of a polymeric material (including monomeric ormacromeric materials), as used herein, refers to the number-averagemolecular weight unless otherwise specifically noted or unless testingconditions indicate otherwise.

A “polymer” means a material formed by polymerising and/or crosslinkingone or more monomers, macromers and/or oligomers and having two or morerepeat units.

A “semiconducting binder” as used herein refers to an organic binderthat is between a conductor and an insulator in its ability to conductelectrical current.

Preferably, according to the present invention, a semiconductingmaterial, composition or layer is one which has an electricalconductivity in the range of 10³ to 10⁻⁸ siemens per centimetre, morepreferably between 500 to 10⁻⁷, more preferably between 300 to 10⁻⁶,more preferably between 250 to 10⁻⁵, more preferably between 10 to 10⁻⁵siemens per centimetre, more preferably greater than 10⁻⁴ or 10⁻³siemens per centimetre. The conductivity of the material or compositionis measured according to ASTM D4308-10. The same test may be used tomeasure the conductivity of the compositions, layers and polyacenecompounds of the present invention.

As used herein, the term “alkyl” group refers to a straight or branchedsaturated monovalent hydrocarbon radical, having the number of carbonatoms as indicated. By way of non limiting example, suitable alkylgroups include, methyl, ethyl, propyl, n-butyl, t-butyl, iso-butyl anddodecanyl.

As used herein, the term “alkoxy” group include without limitation,methoxy, ethoxy, 2-methoxyethoxy, t-butoxy, etc.

As used herein, the term “amino” group includes, without limitation,dimethylamino, methylamino, methylphenylamino, phenylamino, etc.

The term “carbyl” refers to any monovalent or multivalent organicradical moiety which comprises at least one carbon atom other withoutany non-carbon atoms (—C≡C), or optionally combined with at least onenon-carbon atoms such as N, O, S, P, SI, Se, As, Te or Ge (for examplecarbonyl etc.).

The term “hydrocarbon” group denotes a carbyl group that additionallycontains one or more H atoms and optionally contains one or more heteroatoms.

A carbyl or hydrocarbyl group comprising 3 or more carbon atoms may belinear, branched and/or cyclic, including spiro and/or fused rings.

Preferred carbyl or hydrocarbyl groups include alkyl, alkoxy,alkylcarbonyl, alkylcarbonyloxy, alkoxycarbonyloxy, each of which isoptionally substituted and has 1 to 40, preferably 1 to 18 carbon atoms,furthermore optionally substituted aryl, aryl derivative or aryloxyhaving 6 to 40, preferably 6 to 18 carbon atoms, furthermorealkylaryloxy, arylcarbonyl, aryloxycarbonyl, arylcarbonyloxy andaryloxycarbonyloxy, each or which is optionally substituted and has 7 to40, more preferable 7 to 25 carbon atoms.

The carbyl or hydrocarbyl group may be saturated or unsaturated acyclicgroup, or a saturated or unsaturated cyclic group. Unsaturated acyclicor cyclic groups are preferred, especially alkenyl and alkynyl groups(especially ethynyl).

In the polyacenes of the present invention, the optional substituents onthe said C₁-C₄₀ carbyl or hydrocarbyl groups for R₁-R₁₄ etc. preferablyare selected from: silyl, sulpho, sulphonyl, formyl, amino, imino,nitrilo, mercapto, cyano, nitro, halo, C₁₋₄ alkyl, C₆₋₁₂ aryl, C₁₋₄alkoxy, hydroxy and/or all chemically possible combinations thereof.More preferable among these optional substituents are silyl and C₆₋₁₂aryl and most preferable is silyl.

“Substituted alkyl group” refers to an alkyl group having one or moresubstituents thereon, wherein each of the one or more substituentscomprises a monovalent moiety containing one or more atoms other thancarbon and hydrogen either alone (e.g., a halogen such as F) or incombination with carbon (e.g., a cyano group) and/or hydrogen atoms(e.g., a hydroxyl group or a carboxylic acid group).

“Alkenyl group” refers to a monovalent group that is a radical of analkene, which is a hydrocarbon with at least one carbon-carbon doublebond. The alkenyl can be linear, branched, cyclic, or combinationsthereof and typically contains 2 to 30 carbon atoms. In someembodiments, the alkenyl contains 2 to 20, 2 to 14, 2 to 10, 4 to 10, 4to 8, 2 to 8, 2 to 6, or 2 to 4 carbon atoms. Exemplary alkenyl groupsinclude, but are not limited to, ethenyl, propenyl, and butenyl.

“Substituted alkenyl group” refers to an alkenyl group having (i) one ormore C—C double bonds, and (ii) one or more substituents thereon,wherein each of the one or more substituents comprises a monovalentmoiety containing one or more atoms other than carbon and hydrogeneither alone (e.g., a halogen such as F) or in combination with carbon(e.g., a cyano group) and/or hydrogen atoms (e.g., a hydroxyl group or acarboxylic acid group).

“Alkynyl group” refers to a monovalent group that is a radical of analkyne, a hydrocarbon with at least one carbon-carbon triple bond. Thealkynyl can be linear, branched, cyclic, or combinations thereof andtypically contains 2 to 30 carbon atoms. In some embodiments, thealkynyl contains 2 to 20, 2 to 14, 2 to 10, 4 to 10, 4 to 8, 2 to 8, 2to 6, or 2 to 4 carbon atoms. Exemplary alkynyl groups include, but arenot limited to, ethynyl, propynyl, and butynyl.

“Substituted alkynyl group” refers to an alkynyl group having (i) one ormore C—C triple bonds, and (ii) one or more substituents thereon,wherein each of the one or more substituents comprises a monovalentmoiety containing one or more atoms other than carbon and hydrogeneither alone (e.g., a halogen such as F) or in combination with carbon(e.g., a cyano group) and/or hydrogen atoms (e.g., a hydroxyl group or acarboxylic acid group or a silyl group).

“Cycloalkyl group” refers to a monovalent group that is a radical of aring structure consisting of 3 or more carbon atoms in the ringstructure (i.e., only carbon atoms in the ring structure and one of thecarbon atoms of the ring structure is the radical).

“Substituted cycloalkyl group” refers to a cycloalkyl group having oneor more substituents thereon, wherein each of the one or moresubstituents comprises a monovalent moiety containing one or more atoms(e.g., a halogen such as F, an alkyl group, a cyano group, a hydroxylgroup, or a carboxylic acid group).

“Cycloalkylalkylene group” refers to a monovalent group that is a ringstructure consisting of 3 or more carbon atoms in the ring structure(i.e., only carbon atoms in the ring), wherein the ring structure isattached to an acyclic alkyl group (typically, from 1 to 3 carbon atoms,more typically, 1 carbon atom) and one of the carbon atoms of theacyclic alkyl group is the radical. “Substituted cycloalkylalkylenegroup” refers to a cycloalkylalkylene group having one or moresubstituents thereon, wherein each of the one or more substituentscomprises a monovalent moiety containing one or more atoms (e.g., ahalogen such as F, an alkyl group, a cyano group, a hydroxyl group, or acarboxylic acid group).

“Aryl group” refers to a monovalent group that is a radical of anaromatic carbocyclic compound. The aryl can have one aromatic ring orcan include up to 5 carbocyclic ring structures that are connected to orfused to the aromatic ring. The other ring structures can be aromatic,non-aromatic, or combinations thereof. Examples of preferred aryl groupsinclude, but are not limited to, phenyl, 2-tolyl, 3-tolyl, 4-tolyl,biphenyl, 4-phenoxyphenyl, 4-fluorophenyl, 3-carbomethoxyphenyl,4-carbomethoxyphenyl, terphenyl, anthryl, naphthyl, acenaphthyl,anthraquinonyl, phenanthryl, anthracenyl, pyrenyl, perylenyl, andfluorenyl.

“Substituted aryl group” refers to an aryl group having one or moresubstituents on the ring structure, wherein each of the one or moresubstituents comprises a monovalent moiety containing one or more atoms(e.g., a halogen such as F, an alkyl group, a cyano group, a hydroxylgroup, or a carboxylic acid group).

“Arylalkylene group” refers to a monovalent group that is an aromaticring structure consisting of 6 to 10 carbon atoms in the ring structure(i.e., only carbon atoms in the ring structure), wherein the aromaticring structure is attached to an acyclic alkyl group having one or morecarbon atoms (typically, from 1 to 3 carbon atoms, more typically, 1carbon atom) and one of the carbons of the acyclic alkyl group is theradical.

“Substituted arylalkylene group” refers to an arylalkylene group havingone or more substituents thereon, wherein each of the one or moresubstituents comprises a monovalent moiety containing one or more atoms(e.g., a halogen such as F, an alkyl group, a cyano group, a hydroxylgroup, or a carboxylic acid group).

“Acetyl group” refers to a monovalent radical having the formula—C(O)CH₃.

“Heterocyclic ring” refers to a saturated, partially saturated, orunsaturated ring structure comprising at least one of O, N, S and Se inthe ring structure.

“Substituted heterocyclic ring” refers to a heterocyclic ring having oneor more substituents bonded to one or more members of the ringstructure, wherein each of the one or more substituents comprises amonovalent moiety containing one or more atoms (e.g., a halogen such asF, an alkyl group, a cyano group, a hydroxyl group, or a carboxylic acidgroup).

“Carbocyclic ring” refers to a saturated, partially saturated, orunsaturated ring structure comprising only carbon in the ring structure.

“Substituted carbocyclic ring” refers to a carbocyclic ring having oneor more substituents bonded to one or more members of the ringstructure, wherein each of the one or more substituents comprises amonovalent moiety containing one or more atoms (e.g., a halogen such asF, an alkyl group, a cyano group, a hydroxyl group, or a carboxylic acidgroup).

“Ether group” refers to a —R_(a)—O—R_(b) radical wherein R_(a) is abranched or unbranched alkylene, arylene, alkylarylene or arylalkylenehydrocarbon and R_(b) is a branched or unbranched alkyl, aryl, alkylarylor arylalkyl hydrocarbon.

“Substituted ether group” refers to an ether group having one or moresubstituents thereon, wherein each of the one or more substituentscomprises a monovalent moiety containing one or more atoms other thancarbon and hydrogen either alone (e.g., a halogen such as F) or incombination with carbon (e.g., a cyano group) and/or hydrogen atoms(e.g., a hydroxyl group or a carboxylic acid group).

Unless otherwise defined, a “substituent” or “optional substituent” ispreferably selected from the group consisting of halo (I, Br, Cl, F),CN, NO₂, NH₂, —COOH and OH.

EXAMPLES OF THE PRESENT INVENTION

The following examples of the present invention are merely exemplary andshould not be viewed as limiting the scope of the invention.

Measurement of the Capacitance of the Polymer Binder

The polymer binder was diluted with tetralin in order to lower itsviscosity and make it possible to obtain a film thickness of ˜1 micronwhen spin coated for the spin speed range 1000-2000 rpm/s. The polymerbinder solution was spin coated at 500 rpm for 10 seconds, followed by1500 rpm for 30 seconds, onto ITO coated and cleaned 1×1 inch glasssubstrates.

To clean the ITO coated substrates they were submerged in a 3% solutionof DECon 90 and put in an ultrasonic bath (water temperature >65° C.),washed with deionised water, submerged in deionised water and put in anultrasonic bath (water temperature >65° C.), washed a further time withdeionised water, submerged in isopropyl alcohol and then put in anultrasonic bath (water temperature >65° C.), and then spin dried.

After deposition of the polymer binder the substrate was annealed on ahotplate at 120° C. for 5 minutes.

The substrate was then covered with a capacitance shadow mask, and topelectrodes were deposited by evaporation of gold using a thermaldeposition method. In order to determine the exact thickness of thepolymer binder layer, the thickness was measured using a Dektak 3030profilometer (available from Veeco, Plainview N.Y.) at three differentpositions and averaged; these values were subsequently used to calculatethe dielectric constants of the polymer binders.

Capacitance measurements were then carried out using impedance analyserAgilent 43961A and a probe station. In order to improve the electricalcontact between the ITO back electrode and the external probe electrode,a conductive silver paste was applied. The sample being measured wasplaced in a metal box on the metal plate to ensure minimum influencefrom the external environment.

Before each set of measurements was obtained, the analyser wascalibrated using the 43961A Impedance Test Kit as a compensation routinewas carried out to account for internal capacitance of the analyser andtest fixture. The measurement calibration was carried out with open andshorted circuit; the dielectric constant was calculated using thefollowing equation:

C=∈×∈ _(o)×(A/d).

Wherein C is the capacitance (Farads), A is the area (m²), d is thecoating thickness (m), ∈ is the dielectric constant (permittivity), and∈_(o) is the permittivity of free space and is taken as 8.8854×10⁻¹²F/m.

As a reference sample, a polystyrene sample (Mw˜350,000) having athickness of 1 μm was tested. The measured and calculated dielectricconstant of the polystyrene reference was ∈=2.55 at 10,000 Hz, which isin good agreement with the reported value (∈˜2.5), refer to J. R.Wunsch, Polystyrene-Synthesis, Production and Applications, Rapra ReviewReports, 2000, Volume 10, No. 4, page 32.

OTFT Fabrication Method

A substrate (either glass or a polymer substrate such as PEN) ispatterned with Au source drain electrodes either by a process of thermalevaporation through a shadow mask or by photolithography (an adhesionlayer of either Cr or Ti is deposited on the substrate prior todeposition of Au). The Au electrodes can then optionally be cleanedusing an O₂ plasma cleaning process. A solution of organic semiconductorin binder is then applied by spin coating (the sample is flooded withthe solution and the substrate is then spun at 500 rpm for 5 secondsthen 1500 rpm for 1 minute). The coated substrate is then dried in airon a hot stage. The dielectric material, for example 3 wt % PTFE-AF 1600(Sigma-Aldrich cat #469610) dissolved in FC-43 was then applied to thesubstrate by spin coating (sample flooded then spun at 500 rpm for 5seconds then 1500 rpm for 30 seconds). The substrate was then dried inair on a hot stage (100° C. for 1 minute). A gate electrode (Au) is thendefined over the channel area by evaporation through a shadow mask.

The mobility of the OTFT for the binders is characterised by placing ona manual probe station connected to a Keithley SCS 4200 semiconductoranalyzer. The source drain voltage (V_(DS)) is set at −2V (linear) or−40V (saturation) and the gate voltage (V_(G)) scanned from +20V to−60V. Drain current is measured and mobility calculated from thetransconductance.

The mobility of the OTFT for the formulations is characterised byplacing on a semi-auto probe station connected to a Keithley SCS 4200semiconductor analyzer. The source drain voltage (V_(DS)) is set at −2Vand the gate voltage (V_(G)) scanned from +20V to −40V. Drain current ismeasured and mobility calculated from the transconductance.

In linear regime, when |V_(G)|>|V_(DS)|, the source-drain current varieslinearly with V_(G). Thus the field effect mobility (μ) can becalculated from the gradient (S) of I_(DS) vs. V_(G) given by equation 1(where C_(i) is the capacitance per unit area, W is the channel widthand L is the channel length):

$\begin{matrix}{S = \frac{\mu \; {WC}_{i}V_{DS}}{L}} & {{Equation}\mspace{14mu} 1}\end{matrix}$

In the saturation regime, the mobility is determined by finding theslope of I_(DS) ^(1/2) vs. V_(G) and solving for the mobility (Equation2)

$\begin{matrix}{I_{DS} \approx \frac{{WC}_{i}{\mu \left( {V_{GS} - V_{T}} \right)}^{2}}{2L}} & {{Equation}\mspace{14mu} 2}\end{matrix}$

Method to Determine Molecular Weight and Molecular Weight Distribution

Gel Permeation Chromatography (GPC) analysis was carried out on a WatersAlliance 2695 instrument along with a Waters 2414 refractive index (RI)detector, using an Agilent PL gel 5 μm Mixed-D 300×7.5 mm column elutingwith tetrahydrofuran. Calibration was performed using Agilent “EasiVial”polystyrene standards (PL2010-0400)

EXAMPLES 1. Preparation of bis(N-4-chlorophenyl)-2-methoxyphenylamine(Compound 1)

A mixture of 2-methoxyaniline (Sigma-Aldrich A88182, 20.0 g, 162 mmol, 1equiv), 1-chloro-4-iodobenzene (96.8 g, 406 mmol, 2.5 equiv), copperpowder (31.0 g, 488 mmol, 3.0 equiv), potassium carbonate (80.8 g, 585mmol, 3.6 equiv), 18-crown-6 (10.7 g, 0.25 equiv, 40.6 mmol) ando-dichlorobenzene (40 mL) were charged to a nitrogen purged 500 mL roundbottom flask fitted with a Dean-Stark apparatus (including a condenser)and a thermometer. The reaction mixture was heated to 190° C. withstirring. The reaction was monitored by thin-layer chromatography(consumption of the aniline/appearance of product). When the reaction ascomplete (48 hrs), the mixture was allowed to cool to room temperature.The mixture was then filtered through a Whatman GF/F filter to removeinorganic solids. The filter cake was washed with dichloromethane (200mL). The filtrate was then added to a separating funnel containing water(100 mL). The mixture was then agitated and the organic and aqueouslayers separated. The organic layer was died over MgSO₄, filtered andconcentrated to give a dark brown viscous oil. The mixture was thenpurified by flash column chromatography (gradient elution: 20%-50%dichloromethane in heptane) to give an off-white solid.Recrystallisation from methanol gave the product as a colourless solid(25.1 g, 73.0 mmol, 45%). ¹H NMR (500 MHz, CDCl₃) 7.37-7.00 (12H, m,aromatic), 3.79 (3H, s, OCH ₃).

2. Preparation of High Molecular Weight Binder (Oligomer 1)

A flame dried 500 mL round-bottom flask fitted with a condenser,thermometer and nitrogen inlet was charged with nickel (11) chloride(0.20 g, 1.54 mmol), zinc powder (10.80 g, 165 mmol), 2,2′-bipyridyl(0.35 g, 2.24 mmol), triphenylphosphine (7.80 g, 29.7 mmol) andanhydrous N,N-dimethylacetamide (200 mL). The mixture was heated to 70°C., at which point the reaction mixture becomes dark brown/red in colour(characteristic of the formation of a nickel (0) species). The mixturewas stirred at 70° C. for a further 30 minutes.Bis(N-4-chlorophenyl)-2-methoxyphenylamine (Compound 1, 20.0 g, 58.1mmol) was then added in a single charge. After approx. 90 minutes solidmaterial began to precipitate from the reaction mixture. Toluene (70 mL)and another charge of nickel (II) chloride (0.2 g, 1.54 mmol) were addedand the reaction mixture was stirred at 70° C. overnight. 0.10 Thereaction mixture was allowed to cool and was then filtered through aWhatman Grade 1 filter paper. The filtered solid was then dissolved intoluene (100 mL). Concentrated hydrochloric acid was then added dropwiseto destroy excess zinc. The phases were then separated and the organicphase concentrated to give a pale yellow semisolid. This was dissolvedin THF (100 mL) and poured into MeOH (100 mL). The precipitated solidwas collected by filtration and dried (16.1 g, n_(av)=35, M_(n)=9555).

2.1 Purification

The solid obtained above was purified by column chromatography (Silicagel 60; eluent 50% dichloromethane in heptane). The columned fractionswere then concentrated, dissolved in THF (60 mL) and poured into MeOH(150 mL). The precipitated solid was collected by filtration and dried(14.0 g, n_(av)=42, M_(n)=11466). The chromatography/precipitation wasrepeated two more times (13.5 g, n_(av)=48, M_(n)=13104).

2.2 Reduction (Oligomer 2)

Ammonium formate (45.0 g), Pd/C (10% Pd, 14.0 g) and water (60 mL) werecharged to a 500 mL round bottom flask. Oligomer 1 in toluene (120 mL)was then added and the mixture was heated gradually to 85° C. for 8hours. The mixture was allowed to cool to room temperature overnight.More ammonium formate (20.0 g) and Pd/C (7.0 g) were added and themixture heated to 85° C. for 8 hours. The mixture was then allowed tocool to room temperature overnight. The catalyst was then removed byfiltration through a plug of Celite. The organic layer was separated,dried over MgSO₄, filtered and concentrated. The mixture was thenpurified by sequential column chromatography (Silica gel 60, eluent 50%dichloromethane in heptane) and precipitation (dissolved in 60 mL THF,poured into 150 mL MeOH and filtered) three times. The final solid wasdried (12.8 g, n_(av)=48, M_(n)=13104).

3. Preparation of Low Molecular Weight Binder (Oligomer 3)

A flame dried 500 mL round-bottom flask fitted with a condenser,thermometer and nitrogen inlet was charged with nickel (II) chloride(0.20 g, 1.54 mmol), zinc powder (10.80 g, 165 mmol), 2,2′-bipyridyl(0.35 g, 2.24 mmol), triphenylphosphine (7.80 g, 29.7 mmol) andanhydrous N,N-dimethylacetamide (150 mL). The mixture was heated to 70°C., at which point the reaction mixture becomes dark brown/red in colour(characteristic of the formation of a nickel (0) species). The mixturewas stirred at 70° C. for a further 30 minutes.Bis(N-4-chlorophenyl)-2-methoxyphenylamine (Compound 1, 20.0 g, 58.1mmol) was then added in a single charge. After 2 hours toluene (200 mL)was added and the reaction was cooled to room temperature. Concentratedhydrochloric acid as added dropwise to destroy excess zinc. The organiclayer was separated and the solvent removed in vacuo. The crude oilobtained was then dissolved in THF (60 mL) and was poured into MeOH (150mL). The precipitated solid was collected by filtration and dried (15.5g, n_(av)=1, M_(n)=3003). The material was then purified as describedbelow.

3.1 Purification

The solid obtained above was purified by column chromatography (Silicagel 60; eluent 50% dichloromethane in heptane). The columned fractionswere then concentrated, dissolved in THF (60 mL) and poured into MeOH(150 mL). The precipitated solid was collected by filtration and dried(12.4 g, n_(av)=14). The chromatography/precipitation was repeated twomore times (11.5 g, n_(av)=14, M_(n)=3822).

Oligomer 3 had a permittivity of 3.5 Fm⁻¹ at 1000 Hz.

Formulation 1 Oligomer 3 and polyacene 1,(1,4,8,11-tetramethyl-6,13-bis(trimethylsilylethynyl)pentacene) (1:1ratio by weight) were dissolved in 1,2,3,4-tetrahydronaphthalene at 2%total solids and spin coated (500 rpm for 5 s, then 1500 rpm for 60 s)onto patterned Au source/drain electrodes (50 nm thick Au treated with a10 mM solution of pentafluorobenzene thiol in isopropyl alcohol). Thefluoropolymer dielectric Cytop (Asahi Chemical Co.) was spin coated ontop (500 rpm for 5 s then 1500 rpm for 20 s). Finally an Au gateelectrode was deposited by shadow mask evaporation.

Mobility was 2.5 cm²V⁻¹ s⁻¹ (linear mobility, channel length L=30 μm).

3.2 Reduction (Oligomer 4)

Ammonium formate (45.0 g), Pd/C (10% Pd, 14.0 g) and water (60 mL) werecharged to a 500 mL round bottom flask. Oligomer 4 in toluene (120 mL)was then added and the mixture was heated gradually to 85° C. for 8hours. The mixture was allowed to cool to room temperature overnight.More ammonium formate (20.0 g) and Pd/C (7.0 g) were added and themixture heated to 85° C. for 8 hours. The mixture was then allowed tocool to room temperature overnight. The catalyst was then removed byfiltration through a plug of Celite. The organic layer was separated,dried over MgSO₄, filtered and concentrated. The mixture was thenpurified by sequential column chromatography (Silica gel 60, eluent 50%dichloromethane in heptane) and precipitation (dissolved in 60 mL THF,poured into 150 mL MeOH and filtered) three times. The final solid wasdried (10.2 g, n_(av)=14, M_(n)=3822).

4. Preparation of 2-Methoxy Polytriarylamine Oligomer by Polymerising2-Methoxy Aniline with 4,4′-Dibromobiphenyl (Oligomer 5)

A mixture of 2-methoxyaniline (Sigma-Aldrich A88182, 1.54 g, 12.5 mmol),4,4′-biphenyl (Sigma-Aldrich 229237, 7.80 g, 25 mmol, 2 eq.) sodiumtert-butoxide (NaO^(t)Bu) (5.05 g, 105 mmol) in toluene (50 mL) wasdegassed by passing a stream of nitrogen through the solution for 15minutes. Pd₂dba₃ (Sigma-Aldrich 328774, 0.06 g, 0.15 mol %) andP(tBu)₂-o-biphenyl (Sigma-Aldrich 638439, 0.07 g, 0.65 mol %) were thenadded and the mixture heated to 85 deg C. After approx. 1 hour HPLCconfirmed the presence of oligomers. A further charge of2-methoxyaniline (3.08 g, 25.0 mmol) and NaO^(t)Bu (5.05 g, 105 mmol)were added. After another 2 hours 4,4′-biphenyl (7.80 g), Pd₂dba₃ (0.06g) and P(tBu)₂-o-biphenyl (0.07 g) were added and the mixture stirred at85 deg C. overnight. After a total reaction time of 21 hours the mixturewas allowed to cool to room temperature. The mixture was poured intowater (150 mL) and filtered through a GF/A filter and the cake washedwith THF (50 mL). The organic layer of the filtrate was separated andthe aqueous layer was extracted with THF (3×30 mL). The organic layerswere combined, dried (MgSO₄), filtered and concentrated to give a brownsemi-solid (15.37 g). The crude product was dissolved in THF (50 mL) andadded dropwise into methanol (100 mL). The precipitated solid wascollected by filtration under suction using a Buchner funnel, washedwith methanol (20 mL) and pulled dry (12.3 g). The solid was purified bydry column chromatography eluting with dichloromethane. The fractionscontaining product were concentrated (11.7 g), the product dissolved inTHF (50 mL) and added dropwise into methanol (100 mL). The precipitatedsolid was collected by filtration using a Buchner funnel and was thendried in a vacuum oven (40 deg C.) overnight to give the product as apale yellow amorphous solid (9.35 g) which was characterised as follows:GPC: Mn=2036 Daltons, N_(av)=7.

Oligomer 5 had a permittivity of 3.4 Fm⁻¹ at 1000 Hz; a mobility of6.3×10⁻⁶ cm²V⁻¹ s⁻¹ (linear mobility) and 2.4×10^(0.5) cm²V⁻¹ s⁻¹(saturation mobility) at a channel length, L=40 μm.

4.1: Preparation of 4-Methoxy Polytriarylamine Oligomer (2) byPolymerising 4-Methoxy Aniline with 4,4′-Dibromobiphenyl (Oligomer 6)

A mixture of 4-methoxyaniline (Sigma-Aldrich A88255, 3.08 g, 25.0 mmol),4,4′-biphenyl (15.60 g, 50 mmol, 2 eq.) sodium tert-butoxide (10.10 g,105 mmol) in toluene (50 mL) was degassed by passing a stream ofnitrogen through the solution for 15 minutes. Pd₂dba₃ (0.12 g, 0.3 mol%) and P(tBu)₂-o-biphenyl (0.14 g, 1.3 mol %) were then added and themixture heated to 85 deg C. After approx. 1 hour, HPLC confirmed thepresence of oligomers. A further charge of 4-methoxyaniline (6.16 g,50.0 mmol) and NaO^(t)Bu (10.10 g, 105 mmol) were then added. After afurther 2 hours, 4,4′-biphenyl (15.6 g), Pd₂dba₃ (0.12 g) andP(tBu)₂-o-biphenyl (0.14 g) were added and the mixture stirred at 85 degC. overnight. After a total reaction time of 18 hours the mixture wasallowed to cool to room temperature. The mixture was then poured intowater (˜300 mL), filtered through a GF/A filter and the cake washed withTHF (50 mL). The organic layer of the filtrate was separated and theaqueous layer was extracted with THF (3×30 mL). The organic layers werecombined, dried (MgSO₄), filtered and concentrated to give a brownsemi-solid (19.79 g). The crude product was dissolved in THF (50 mL) andadded dropwise into methanol (100 mL). The precipitated solid wascollected by filtration under suction using a Buchner funnel and washedwith methanol (30 mL) (16.41 g). The solid was purified by dry columnchromatography (eluent: dichloromethane/THF). The fractions containingproduct were concentrated (14.4 g), the product dissolved in THF (50 mL)and added dropwise into methanol (100 mL). The precipitated solid wascollected by filtration using a Buchner funnel. The material waspurified using dry column chromatography, eluting with dichloromethane(DCM; 7.30 g). The product was then dissolved in THF (50 mL) andprecipitated into methanol (100 mL). The solid was collected byfiltration and was then dried in a vacuum oven (40 deg C.) overnight togive the product as a pale yellow amorphous solid (6.40 g) which wascharacterised as follows: GPC Mn=1307 Daltons, N_(av)=5.

Oligomer 6 had a permittivity of 3.5 Fm⁻¹ at 1000 Hz; a mobility of4.2×10⁻⁵ cm²V⁻¹ s⁻¹ (linear mobility) and 1.0×10⁻⁴ cm²V⁻¹ s⁻¹(saturation mobility) at a channel length, L=40 μm.

Formulation 2

Oligomer 6 and polyacene 1,(1,4,8,11-tetramethyl-6,13-bis(trimethylsilylethynyl)pentacene) (1:1ratio by weight) were dissolved in 1,2,3,4-tetrahydronaphthalene at 2%total solids and spin coated (500 rpm for 5 s, then 1500 rpm for 60 s)onto patterned Au source/drain electrodes (50 nm thick Au treated with a10 mM solution of pentafluorobenzene thiol in isopropyl alcohol). Thefluoropolymer dielectric Cytop (Asahi Chemical Co.) was spin coated ontop (500 rpm for 5 s then 1500 rpm for 20 s). Finally an Au gateelectrode was deposited by shadow mask evaporation. Mobility was 4.00cm²V⁻¹ s¹ (linear mobility, channel length L=30 μm).

6. Reduction of the 4-Methoxy Polytriarylamine Oligomer to AffordOligomer 7

4-methoxy polymer (Oligomer 6, 2.50 g) was dissolved in toluene (20 mL)in a three-necked flask fitted with a condenser. Ammonium formate (10.0g, 159 mmol) and Pd on activated carbon (10% Pd, 2.5 g) were added andthe mixture heated to 65 deg C. After 14 hours a further charge ofammonium formate (10.0 g, 159 mmol) and Pd on activated carbon wereadded and the mixture stirred at 65 deg C. for a further 6 hours. Themixture was allowed to cool, water (20 mL) was added and the organiclayer separated. The organic layer was dried over MgSO₄, filtered andconcentrated to give a cream coloured semi-solid (2.31 g). The solid wasdissolved in THF (30 mL) and the oligomer precipitated by pouring slowlyinto methanol (60 mL) with stirring. The precipitated solid wascollected by filtration. The solid was then purified by dry columnchromatography (eluent 1:1 DCM:THF) three times. The mixture as thendissolved in THF (30 mL) and precipitated into methanol (60 mL) andcollected by filtration. (2.20 g), which was characterised as follows:GPC Mn=1313 Daltons, N_(av)=5.

Oligomer 7 had a permittivity of 3.5 Fm⁻¹ at 1000 Hz.

Formulation 3

Oligomer 7 and polyacene 1(1,4,8,11-tetramethyl-6,13-bis(trimethylsilylethynyl)pentacene) (1:1ratio by weight) were dissolved in 1,2,3,4-tetrahydronaphthalene at 2%total solids and spin coated (500 rpm for 5 s, then 1500 rpm for 60 s)onto patterned Au source/drain electrodes (50 nm thick Au treated with a10 mM solution of pentafluorobenzene thiol in isopropyl alcohol). Thefluoropolymer dielectric Cytop (Asahi Chemical Co.) was spin coated ontop (500 rpm for 5 s, then 1500 rpm for 20 s). Finally an Au gateelectrode was deposited by shadow mask evaporation.

Mobility was 4.5 cm²V⁻¹ s⁻¹ (linear mobility, channel length L=30 μm)and 4.1 cm²V⁻¹ s⁻¹ (linear mobility, channel length L=4 μm).

7. Preparation of Bis(N-4-Chlorophenyl)-4-Methoxyphenylamine (Compound2)

A mixture of 4-methoxyaniline (60.50 g, 491 mmol),1-chloro-4-iodobenzene (292.87 g, 1228 mmol), anhydrous potassiumcarbonate (244.40 g, 1770 mmol), copper powder (93.66 g, 1474 mmol),18-crown-6 ether (32.46 g, 123 mmol) and anhydrous ortho-dichlorobenzene(o-DCB, 100 mL), were charged to a 700 mL flange flask, fitted with aDean-Stark trap, thermometer, overhead stirrer and water condenser, andflushed with nitrogen for 10 mins. The mixture was heated to 170 deg C.and stirred for. After 72 hours the mixture was allowed to cool to roomtemperature and was then filtered through a GF/A filter paper. The cakewas washed with DCM (800 mL and the combined filtrates were washed withwater (HPLC grade, 250 mL×2). The combined aqueous layers wereback-extracted with DCM (200 mL×2), combine and dried over MgSO₄. Thefilter cake was washed with DCM (150 mL×2) and the combined filtratesconcentrated in vacuo to give a brown semi-solid (227.12 g). The crudeproduct was dissolved in heptane (200 mL) and purified by dry columnchromatography (gradient elution: heptane-10% DCM: 1.5 heptane) gave apale yellow viscous oil, 101.87 g. ¹H NMR (500 MHz, CDCl₃) 7.16 (4H, d,J=8.8 Hz), 7.02 (2H, d, J=8.8 Hz), 6.93 (4H, d, J=8.8 Hz), 6.84 (2H, d,J=8.8 Hz), 3.80 (3H, s, OCH₃).

8. Preparation of 4-Methoxy Polytriarylamine Oligomer 8 by Polymerisingthe Amine Monomer (as Prepared in Example 2(c))

A 500 mL flange flask, fitted with a thermometer, overhead stirrer andwater condenser, was flame-dried under nitrogen purge to 100 deg C.,then allowed to cool to ambient temperature. Nickel(II) chloride (0.098g, 0.76 mmol), zinc powder (5.92 g, 90.61 mmol), 2′-bipyridyl (0.18 g,1.13 mmol), triphenylphosphine (3.94 g, 15.03 mmol) and anhydrous DMAc(90 mL) were charged in and the grey suspension stirred at 20 deg C. for15 mins. The mixture was then heated to 70 deg C. The burgundy colour ofthe catalyst forms as the temperature increases. Stirring was continuedat 70 deg C. for a further 20 mins to allow the catalyst to stabilise,then a solution of the 4-methoxy monomer (Example 2(c), 10 g) inanhydrous DMAc (10 mL) was added to the flange flask and stirringcontinued for 4.5 h. After 4 h, solids start to precipitate. The mixturewas allowed to cool to 25 deg C. Toluene (210 mL) was added and thestirred mixture was then cooled in an ice/water bath to 15 deg C., thenconcentrated hydrochloric acid (37%, 35 mL) was added dropwise (exothermto 30 deg C.). The mixture was stirred for 10 mins, filtered and thefiltrate transferred to a separating funnel. The filter cake werestirred in THF (300 mL) and filtered. This filtrate was combined withthe organic layer from the separating funnel and concentrated in vacuoto give a yellow semi-solid (20.33 g). The material was dissolved in THF(60 mL) then poured slowly into methanol (180 mL). The precipitatedsolid was isolated by filtration (6.33 g) and purified by dry columnchromatography (eluent: THF). After the final column the solid obtainedwas dissolved in THF (20 mL) and poured slowly into methanol (60 mL),the precipitated solid was collected by filtration under suction using aBuchner funnel, washed with methanol and pulled dry. The solid was thendried in a vacuum oven to give the product as a yellow powder (5.42 g),which was characterised as follows: GPC Mn=2405 Daltons, N_(av)=9.

Oligomer 8 had a permittivity of 3.5 Fm⁻¹ at 1000 Hz; a mobility of6.0×10⁻⁵ cm²V⁻¹ s⁻¹ (linear mobility) and 4.5×10⁻⁴ cm²V⁻¹ s⁻¹(saturation mobility) at a channel length, L=40 μm

Formulation 4

Oligomer 8 and polyacene 1(1,4,8,11-tetramethyl-6,13-bis(triethylsilylethynyl)pentacene) (1:1ratio by weight) were dissolved in 1,2,3,4-tetrahydronaphthalene at 2%total solids and spin coated (500 rpm for 5 s, then 1500 rpm for 60 s)onto patterned Au source/drain electrodes (50 nm thick Au treated with a10 mM solution of pentafluorobenzene thiol in isopropyl alcohol). Thefluoropolymer dielectric Cytop (Asahi Chemical Co.) was spin coated ontop (500 rpm for 5 s, then 1500 rpm for 20 s). Finally an Au gateelectrode was described by shadow mask evaporation.

Mobility was 2.6 cm²V⁻¹ s⁻¹ (linear mobility, channel length L=30 μm).

9. 4-Ethoxy Polytriarylamine Oligomer (Oligomer 9)

Preparation of 4-Ethoxy Polytriarylamine Oligomer by Polymerising4-Ethoxy Aniline with 4,4′-Dibromobiphenyl

A mixture of 4-ethoxyaniline (Sigma-Aldrich P14815, 1.71 g, 12.5 mmol),4,4′-biphenyl (7.80 g, 25.0 mmol) sodium tert-butoxide (5.05 g, 52.6mmol) in toluene (50 mL) was degassed by passing a stream of nitrogenthrough the solution for 15 minutes. Pd₂dba₃ (0.06 g, 0.15 mol %) andP(tBu)₂-o-biphenyl (0.07 g, 0.65 mol %) were then added and the mixtureheated to 85 deg C. After approx. 1 hour HPLC confirmed the presence ofoligomers. Further amounts of 4-ethoxyaniline (3.42 g, 24.9 mmol) andNaO^(t)Bu (5.05 g, 52.6 mmol) were then added. After another 2 hours4,4′-biphenyl (7.80 g, 25.0 mmol), Pd₂dba₃ (0.06 g, 0.15 mol %) andP(tBu)₂-o-biphenyl (0.07 g, 0.65 mol %) were added and the mixturestirred at 85 deg C. overnight. After a total reaction time of 20 hoursthe mixture was allowed to cool to room temperature. The mixture wasthen poured into water (300 mL). The mixture was filtered through a GF/Afilter and the cake washed with toluene (50 mL). The organic layer ofthe filtrate was separated and the aqueous extracted with toluene (3×30mL). The organic layers were combined, dried over MgSO₄, filtered andconcentrated to give a brown semisolid (18.20 g). The crude product wasdissolved in THF (50 mL) and added dropwise into methanol (100 mL). Theprecipitated solid was collected by filtration under suction using aBuchner funnel and pulled dry (13.56 g). The solid was purified by drycolumn chromatography (eluent: dichloromethane). The fractionscontaining product were concentrated, the product (10.92 g) dissolved inTHF (50 mL) and added dropwise into methanol (100 mL). The precipitatedsolid was collected by filtration (Whatman No. 1 paper). The solid wasthen dried in a vacuum oven (40 deg C.) overnight to give the product asa cream coloured amorphous solid (8.10 g), which was characterised asfollows: GPC Mn=1539 Daltons, N_(av)=5.

Oligomer 9 had a permittivity of 3.7 Fm⁻¹ at 1000 Hz; a mobility of6.2×10⁻⁶ cm²V⁻¹ s⁻¹ (linear mobility) and 1.0×10⁻⁶ cm²V⁻¹ s⁻¹(saturation mobility) at channel length, L=40=μm

Formulation 5

Oligomer 9 and polyacene 1(1,4,8,11-tetramethyl-6,13-bis(triethylsilylethynyl)pentacene) (1:1ratio by weight) were dissolved in bromomesitylene at 2% total solidsand spin coated (500 rpm for 5 s, then 1500 rpm for 60 s) onto patternedAu source/drain electrodes (50 nm thick Au treated with a 10 mM solutionof pentafluorobenzene thiol in isopropyl alcohol). The fluoropolymerdielectric Cytop (Asahi Chemical Co.) was spin coated on top (500 rpmfor 5 s then 1500 rpm for 20 s). Finally an Au gate electrode wasdescribed by shadow mask evaporation.

Mobility was 3.1 cm²V⁻¹ s⁻¹ (linear mobility, channel length 100 μm).

10. Preparation of Bis(N-4-Chlorophenyl)-2,4-Dimethoxyphenylamine(Compound 3)

A mixture of 2,4-dimethoxyaniline (TCI Europe D1982, 60.00 g, 391 mmol),1-chloro-4-iodobenzene (233.51 g, 979 mmol), anhydrous potassiumcarbonate (194.89 g, 1410 mmol), copper powder (71.48 g, 1.12 mmol).22g, 1089, 18-crown-6 ether (25.88 g, 97.9 mmol) and anhydrous o-DCB (100mL) were charged to a 700 mL flange flask, fitted with a Dean-Starktrap, thermometer, overhead stirrer and water condenser, and flushedwith nitrogen for 10 mins. The mixture was heated to between 170 deg C.After 3 hr the mixture was allowed to cool to room temperature, DCM (500mL) was added and the mixture filtered through a GF/A filter paper. Thecake washed with DCM (200 mL). The combined filtrates were washed withwater (250 mL×2) and the combined aqueous layers back-extracted with DCM(200 mL×2). The organic layers were combined, dried over MgSO₄ (30 mins)and filtered. The filter cake was washed with further DCM (150 mL×2) andthe combined filtrates concentrated in vacuo to give a brown semi-solid(181.11 g). The crude product was dry loaded onto silica gel andpurified by dry flash column chromatography (gradient elution:heptanes-15% DCM:heptane) to give a colourless solid (72.95 g). Theproduct was recrystallised from heptane to give a colourless crystallinesolid (62.89 g, 43%). ¹H NMR (500 MHz) 7.13 (2H, d, J=8.8 Hz), 7.06 (2H,d, J=9.0 Hz), 6.89 (2H, d, J=8.8 Hz), 6.54 (1H, d, J=2.5 Hz), 6.49 (2H,m), 3.83 (3H, s), 3.65 (3H, s).

11. Preparation of 2,4-Dimethoxy Polytriarylamine Oligomer (10) byPolymerising the Amine Monomer Compound 3

A 500 mL flange flask, fitted with a thermometer, overhead stirrer andwater condenser, was flame-dried under nitrogen purge to 100 deg C.,then allowed to cool to ambient temperature. Nickel(II) chloride (0.10g, 0.76 mmol), zinc powder (5.91 g, 90.6 mmol), 2′-bipyridyl (0.18 g,1.13 mmol), triphenylphosphine (3.93 g, 15.03 mmol) and anhydrous DMAc(90 mL) were charged and the grey suspension stirred at 20 deg C. for 15mins. The mixture was then heated to 70 deg C., during which time thereaction mixture became burgundy in colour (indicative of the formationof a Ni(0) species). Stirring was continued at 70 deg C. for a further20 mins to allow the catalyst to stabilise, then a solution of the2,4-dimethoxy monomer (Example 4(a)) (10.94 g, 29.2 mmol) was added tothe flange flask and stirring continued for 5.5 h. The mixture wasallowed to cool to 25 deg C. Toluene (100 mL) was added and the stirredmixture cooled in an ice/water bath to 15 deg C., then concentratedhydrochloric acid, 37% (35 mL) was added dropwise (exotherm to 30 degC.). The mixture was stirred for 10 mins, filtered and the filtratetransferred to a separating funnel. The organic layer was separated andwas then concentrated in vacuo to give a green semisolid (13.91 g). Thiswas dissolved in THF (40 mL) and precipitated into MeOH (120 mL). Thesolid was isolated by filtration under suction using a Buchner funneland the filter cake washed with MeOH (60 mL). The solid was then driedin a vacuum oven (9.37 g). The solid was purified by dry columnchromatography (eluent THF) three times to give the product as a yellowpowder (8.05 g), which was characterised as follows: GPC Mn=4643Daltons, N_(av)=15.

Oligomer 10 had a permittivity of 3.5 Fm⁻¹ at 1000 Hz; a mobility of3.9×10⁻⁵ cm²V⁻¹ s⁻¹ (linear mobility) and 2.3×10⁻⁴ cm²V⁻¹ s¹ (saturationmobility) at a channel length, L=40 μm

12. Preparation of 3,4,5-Trimethoxy Poytriarylamine Oligomer (Oligomer11) by Polymerizing 3,4,5-Trimethoxy Aniline with 4,4′-Dibromobiphenyl

A mixture of 3,4,5-trimethoxyaniline (Fluorochem 008860, 2.28 g, 12.6mmol), 4,4′-biphenyl (7.80 g) sodium tert-butoxide (5.05 g) in toluene(50 mL) was degassed by passing a stream of nitrogen through thesolution for 15 minutes. Pd₂dba₃ (0.06 g) and P(tBu)₂-o-biphenyl (0.07g) were then added and the mixture heated to 85 deg C. After approx. 1hour, HPLC confirmed the presence of oligomers. Further amounts of4-ethoxyaniline (3.42 g) and NaO^(t)Bu (5.05 g) were then added. Afteranother 2 hours 4,4′-biphenyl (7.8 g), Pd₂dba₃ (0.06 g) andP(tBu)₂-o-biphenyl (0.07 g) were added and the mixture stirred at 85 degC. overnight. After a total reaction time of 20 hours the mixture wasallowed to cool to room temperature. and poured into water (˜300 mL).The mixture was filtered through a GF/A filter and the cake washed withtoluene and THF. The organic layer of the filtrate was separated and theaqueous extracted with THF (3×30 mL). The organic layers were combined,dried (MgSO₄), filtered and concentrated to give a brown semisolid(21.23 g). The crude product was dissolved in THF (50 mL) and addeddropwise into methanol (100 mL). The precipitated solid was collected byfiltration (Whatman No. 1 paper) and pulled dry (15.17 g). The solid waspurified by dry column chromatography (eluent: dichloromethane followedby THF). The THF fractions were concentrated (10.0 g). The product wasdissolved in THF (50 mL) and added dropwise into methanol (100 mL). Theprecipitated solid was collected by filtration (9.6 g). This materialwas purified again by dry column chromatography (eluent THF), thefractions collected were concentrated, dissolved in THF (50 mL) andpoured into methanol (100 mL). The solid was collected by filtration andthen dried in a vacuum oven (40 deg C.) overnight to give the product asa cream coloured amorphous solid (7.3 g), which was characterised asfollows: GPC Mn=2502 Daltons, N_(av)=8.

Oligomer 11 had a permittivity of 3.9Fm⁻¹ at 1000 Hz; a mobility of6.0×10⁻⁶ cm²V⁻¹ s⁻¹ (linear mobility) and 1.4×10⁻⁶ cm²V⁻¹ s⁻¹(saturation mobility) at a channel length, L=40 μm

Formulation 6

Oligomer 11 and polyacene 1(1,4,8,11-tetramethyl-6,13-bis(triethylsilylethynyl)pentacene) (1:1ratio by weight) were dissolved in tetralin at 2% total solids and spincoated (500 rpm for 5 s, then 1500 rpm for 60 s) onto patterned Ausource/drain electrodes (50 nm thick Au treated with a 10 mM solution ofpentafluorobenzene thiol in isopropyl alcohol). The fluoropolymerdielectric Cytop (Asahi Chemical Co.) was spin coated on top (500 rpmfor 5 s then 1500 rpm for 20 s). Finally an Al gate electrode wasdescribed by shadow mask evaporation.

Mobility was 2.0 cm²V⁻¹ s⁻¹ (linear mobility, channel length 35 μm).

13. Bis(4-chlorophenyl)amine (Compound 4)

4-Chlorobenzeneboronic acid (45.00 g, 287 mmol), hydroxylaminehydrochloride (23.99 g, 345 mmol), anhydrous potassium carbonate (59.66g, 432 mmol), copper(I) bromide (8.23 g, 57 mmol) and MeCN (500 mL) werecharged to a 1 L 3-necked round-bottomed flask, fitted with a two-wayadapter, thermometer, overhead stirrer and air condenser. The bluecoloured reaction mixture was heated to 70 deg C. (became brown afterabout 40 mins). After 66 h, the brown mixture was allowed to cool toroom temperature, and then filtered using a Buchner funnel. The filtercake was washed with acetonitrile (MeCN, 100 mL) and DCM (200 mL). Thecake was then slurried in DCM (200 mL) for 10 mins and filtered viasuction using a Buchner funnel. The combined filtrates were evaporatedin vacuo to afford a brown semisolid (22.28 g). The crude product wasdissolved in DCM and dry loaded onto silica gel then purified by drycolumn chromatography, (gradient elution: 10% DCM: heptane then 20% DCM:heptane) to give the product as a brown solid (10.37 g).Recrystallisation from methanol gave the product as a yellow sold (9.29g, 14%). ¹H NMR (500 MHz) 7.22 (4H, d, J=8.7 Hz), 6.96 (4H, d, J=8.7Hz), 5.63 (1H, b, NH).

14. Preparation of bis(N-4-chlorophenyl)-2-cyanophenylamine

Bis(4-chlorophenyl)amine (Compound 4, 3.07 g, 12.89 mmol) and anhydrousNMP (32 mL) were charged to a 100 mL, 3-necked round-bottomed flask,fitted with a stirrer flea, nitrogen inlet/bubbler, water condenser,thermometer, and a 2M NaOH aqueous solution scrubber, followed by2-fluorobenzonitrile and caesium fluoride. The red mixture was degassedfor 30 mins, and then heated to 175 deg C. (The reaction mixture slowlybecomes dark brown). After 16 h, analysis by liquid chromatography (LC)indicated the reaction was complete. The reaction mixture was allowed tocool to room temperature, diluted with toluene (190 mL) in a conicalflask, dried over magnesium sulphate (30 mins) and filtered via suction.The filter cake washed with further toluene (50 mL) and pulled dry. Thecombined filtrates were evaporated in vacuo (48 deg C.), then under highvacuum at 94 deg C. for 6.5 h, to give to leave a brown oil (4.77 g).The crude product was recrystallized slowly from methanol (45 mL, 10vols), cooled to 6 deg C., filtered and washed with cold (−18 deg C.)methanol (30 mL). This was dried in vacuo (vacuum oven, 40 deg C., 69 h)to give the desired product as brown needles (3.75 g, 85%). ¹H NMR (600MHz, CDCl₃) 7.60 (1H, dd, J=7.8 Hz, 1.6 Hz), 7.52-7.50 (1H, m), 7.24(4H, d, J=8.9 Hz), 7.22-7.17 (2H, m), 6.94 (4H, d, J=8.9 Hz).

15. Preparation of 2-Cyano Polytriarylamine Oligomer (Oligomer 12) byPolymerising the Amine Monomer (Compound 5)

A 250 mL flange flask, fitted with a thermometer, overhead stirrer andwater condenser, was flame-dried under nitrogen purge to 100 deg C.,then allowed to cool to ambient temperature. Nickel(II) chloride (0.05g, 0.39 mmol), zinc powder (3.02 g, 46.13 mmol), 2,2′-bipyridyl (0.090g, 0.58 mmol), triphenylphosphine (2.00 g, 7.65 mmol) and anhydrous DMAc(80 mL) were charged in and the grey suspension stirred at 20 deg C. for25 mins. The mixture was then heated to 70 deg C. (the burgundy colourof the catalyst formed as the mixture was heated) and held at 70 deg C.for a further 30 mins to allow the catalyst to stabilise. The monomer(5.02 g, 14.80 mmol) was added to the flange flask, rinsed in withanhydrous DMAc (10 mL) and stirring continued for 22 hr. The mixture wasallowed to cool to 45 deg C., then toluene (90 mL) was added and thestirred mixture cooled in an ice/water bath to 10 deg C, thenconcentrated hydrochloric acid, 37% (35 mL) was added dropwise (exothermto 25 deg C.; red colour disappears, turns grey/green). THF (80 mL) wasadded, the suspension was stirred for 15 mins and was then transferredto a separating funnel. The organic layer was separated, the aqueouslayer extracted with THF and concentrated give a brown semisolid (11.21g). The residue was taken up in THF (56 mL) then the solution addeddropwise to rapidly-stirred methanol (260 mL) and the precipitated solidwas filtered under suction using a Buchner funnel, the filter cakewashed with methanol (2×40 mL) and pulled dry. The filter cake (22.78 g)was dried in a vacuum oven to leave a yellow powder (3.66 g). Thematerial was purified by dry column chromatography (eluent: THF) threetimes. The product obtained (3.52 g) was dissolved in THF (11 mL) andpoured slowly into methanol (33 mL). The precipitated solid was filteredunder suction using a Buchner funnel, the filter cake washed withmethanol and pulled dry. The solid was then dried in a vacuum oven togive the product as a yellow solid (2.94 g), which was characterised asfollows: GPC Mn=2688 Daltons, N_(av)=8.

Oligomer 12 had a permittivity of 3.5 Fm⁻¹ at 1000 Hz. a mobility of1.9×10⁻⁶ cm²V⁻¹ s⁻¹ (linear mobility) and 3.2×10⁻⁶ cm²V⁻¹ s¹ (saturationmobility) at a channel length, L=40 μm

16. Preparation of Bis(N-4-Chlorophenyl)-4-Cyanophenylamine (Compound 6)

A 500 mL 3-necked round-bottomed flask, fitted with a thermometer,overhead stirrer, a two-way adapter nitrogen inlet/bubbler and watercondenser, was flushed with nitrogen for 30 mins, thenbis(4-chlorophenyl)amine (Example 6(a), 6.22 g, 26.13 mmol),4-bromobenzonitrile (5.23 g, 28.75 mmol), NaO^(t)Bu (3.19 g, 33.18mmol), 1,1′-bis(diphenylphosphino)ferrocene (0.78 g, 1.41 mmol) andanhydrous toluene (280 mL) were charged. The red/brown mixture wasdegassed for 38 mins, and then Pd₂(dba)₃ (0.43 g, 0.47 mmol) was addedand the mixture heated to 80 deg C. under nitrogen. After 18 hrs, anextra 0.5 equiv. of 4-bromobenzonitrile (2.38 g) was added. After afurther two hours another charge of catalyst (Pd₂(dba)₃, 0.43 g),1,1′-bis(diphenylphosphino)ferrocene) (0.78 g 1.41 mmol) and NaO^(t)Bu(1.27 g) were added and heating continued overnight. After a total of 41h, LC indicated the reaction was complete and it was allowed to cool toroom temperature, diluted with water (250 mL), stirred for 10 mins, thentransferred to a separating funnel and the phases allowed to separate.The bottom aqueous phase was removed and back-extracted with toluene(200 mL), and the combined organic extracts washed with brine (250 mL),dried over MgSO₄ (15 mins) and filtered under suction using a Buchnerfunnel and the filter cake washed with toluene (200 mL). The combinedfiltrates were evaporated in vacuo (50 deg C.) to afford a red/brownpowder (14.87 g). The crude product was purified by dry flash columnchromatography (gradient elution: 10% DCM/heptane to 50% DCM/heptane) togive the product as a yellow solid (7.99 g, 90%). ¹H NMR (600 MHz,CDCl₃) 7.44 (2H, d, J=8.6 Hz), 7.28 (4H, d, J=8.6 Hz), 7.04 (4H, d,J=8.6 Hz), 6.95 (2H, d, J=8.6 Hz).

17. Preparation of 4-Cyano Polytriarylamine Oligomer (Oligomer 13) byPolymerising the Amine Monomer (Compound 6)

A 250 mL flange flask, fitted with a thermometer, overhead stirrer andwater condenser, was flame-dried under nitrogen purge to 100 deg C.,then allowed to cool to ambient temperature. Nickel(II) chloride (0.09g, 0.69 mmol) zinc powder (5.38 g, 82.38 mmol), 2,2′-bipyridyl (0.16 g,1.03 mmol), triphenylphosphine (3.58 g, 13.66 mmol) and anhydrous DMAc(80 mL) were charged and the grey suspension stirred at 20 deg C. for 25mins. The burgundy colour of the catalyst formed after 15 mins atambient temperature. The mixture was then heated to 70 deg C. and heldat 70 deg C. for a further 30 mins to allow the catalyst to stabilise.The monomer (Example 7(a), 8.96 g) was added to the flange flask, rinsedin with anhydrous DMAc (10 mL) and stirring continued for 5 h. Themixture was allowed to cool to 45 deg C, then toluene (90 mL) was addedand the stirred mixture cooled in an ice/water bath to 10 deg C., thenconcentrated hydrochloric acid, 37% (35 mL) was added dropwise (exothermto 25 deg C.; mixture became grey/green in colour). THF (80 mL) wasadded; the suspension was stirred for 15 mins and was then transferredto a separating funnel. The organic layer was separated, the aqueouslayer extracted with THF (2×40 mL). The combined organic extracts wereconcentrated give a green semi-solid (21.25 g). The residue was taken upin THF (90 mL) then the solution added dropwise to rapidly-stirredmethanol (260 mL) and the precipitated solid collected by filtrationusing a Buchner funnel and washed with methanol (2×40 mL). The filtercake (40.04 g) was dried in a vacuum oven to afford a deep yellow powder(7.11 g). The material was purified by dry column chromatography(eluent: THF) three times. The product obtained (3.52 g) was dissolvedin THF (1 mL) and poured slowly into methanol (33 mL). The precipitatedsolid was collected by filtration under suction using a Buchner funneland the filter cake washed with methanol (30 mL). The solid (10.09 g)was then dried in a vacuum oven to give the product as a yellow solid(5.38 g), which was characterised as follows: GPC Mn=3341 Daltons,N_(av)=10.

Oligomer 13 had a permittivity of 3.4 Fm⁻¹ at 1000 Hz. a mobility of9.1×10′⁷ cm²V⁻¹ s⁻¹ (linear mobility) and 8.4×10⁷′ cm²V⁻¹ s⁻¹(saturation mobility) at a channel length, L=40 μm

Formulation 7

Oligomer 13 and polyacene 1(1,4,8,11-tetramethyl-6,13-bis(triethylsilylethynyl)pentacene) (1:1ratio by weight) were dissolved in 1,2-dichlorobenzene at 2% totalsolids and spin coated (500 rpm for 5 s, then 1500 rpm for 60 s) ontopatterned Au source/drain electrodes (50 nm thick Au treated with a 10mM solution of pentafluorobenzene thiol in isopropyl alcohol). Thefluoropolymer dielectric Cytop (Asahi Chemical Co.) was spin coated ontop (500 rpm for 5 s then 1500 rpm for 20 s). Finally an Al gateelectrode was described by shadow mask evaporation.

Mobility was 0.6 cm²V⁻¹ s⁻¹ (linear mobility, channel length 35 μm).

Comparative Example 1 2,4 Dimethyl Polytriarylamine Oligomer

2,4-dimethyl polytriarylamine (N_(av)=18) was obtained from High ForceResearch Ltd (Durham, UK). Comparative Example 1 had a permittivity of3.0 Fm⁻¹ at 1000 Hz.

1. An organic semiconductor composition comprising a polyacene compoundand an organic binder, wherein said polyacene compound is selected fromthose of Formulae (4) and (5):

wherein R²⁵, R²⁶ and R²⁷ are independently selected from the groupconsisting of methyl, ethyl and isopropyl; and R¹, R², R³, R⁴, R⁸, R⁹,R¹⁰ and R¹¹ are independently selected from the group consisting ofC₁-C₆ alkyl, C₁-C₆ alkoxy and C₆-C₂₀ aryloxy, and wherein said organicbinder is a semiconducting binder comprising a unit of Formula (6):

wherein Ar₁, Ar₂ and Ar₃, which may be the same or different, eachrepresent, independently if in different repeat units, an optionallysubstituted C₆₋₄₀ aromatic group (mononuclear or polynuclear), whereinat least one of Ar₁, Ar₂ and Ar₃ is substituted with at least one polaror more polarizing group, and n=1 to 20, and said organic binder has apermittivity at 1000 Hz of between 3.4 and 8.0, with the proviso thatthe composition is not a composition containing components (a) and (b),wherein (a) is a 2,4-dimethoxy polytriarylamine polymer having a Mn of3471 g/mol, in which n is 11.5, said polymer having a dielectricconstant of 3.9 and a polydispersity of 2.6; and wherein (b) is1,4,8,11-tetramethyl bis-triethylsilvylethynvylpentacene; wherein (a)and (b) are in a ratio of 2:1 in bromobenzene at 2% by weight totalsolids content.
 2. The composition according claim 1, wherein saidbinder has a permittivity at 1000 Hz of between 4.0 and 6.0.
 3. Thecomposition according claim 1, wherein said binder has a permittivity at1000 Hz of between 3.4 and 4.5. 4-16. (canceled)
 17. The compositionaccording to claim 1, wherein R¹, R², R³, R⁴, R⁸, R⁹, R¹⁰ and R¹¹ areindependently selected from methyl, ethyl, propyl, n-butyl, isobutyl,t-butyl, methoxy, ethoxy, propyloxy and butyloxy groups.
 18. Thecomposition according to claim 1, wherein R¹, R⁴, R⁸ and R¹¹ are thesame and are methyl or methoxy groups and R²⁵, R²⁶ and R²⁷ are the sameand are ethyl or isopropyl groups.
 19. The composition according toclaim 18, wherein R¹, R⁴, R⁸ and R¹¹ are methyl groups and R²⁵, R²⁶ andR²⁷ are ethyl groups.
 20. The composition according to claim 18, whereinR¹, R⁴, R⁸ and R¹¹ are methyl groups and R²⁵, R²⁶ and R²⁷ are isopropylgroups.
 21. The composition according to claim 18, wherein R¹, R⁴, R⁸and R¹¹ are methoxy groups and R²⁵, R²⁶ and R²⁷ are ethyl groups. 22.The composition according to claim 18, wherein R¹, R⁴, R⁸ and R¹¹ aremethoxy groups and R²⁵, R²⁶ and R²⁷ are isopropyl groups.
 23. Thecomposition according to 1, wherein R², R³, R⁹ and R¹⁰ are the same andare methyl or methoxy groups and R²⁵, R²⁶ and R²⁷ are the same and areethyl or isopropyl groups.
 24. The composition according to claim 23,wherein R², R³, R⁹ and R¹⁰ are methyl groups and R²⁵, R²⁶ and R²⁷ areethyl groups.
 25. The composition according to claim 23, wherein R², R³,R⁹ and R¹⁰ are methyl groups and R²⁵, R²⁶ and R²⁷ are isopropyl groups.26. The composition according to claim 23, wherein R², R³, R⁹ and R¹⁰are methoxy groups and R²⁵, R²⁶ and R²⁷ are ethyl groups.
 27. Thecomposition according to claim 23, wherein R², R³, R⁹ and R¹⁰ aremethoxy groups and R²⁵, R²⁶ and R²⁷ are isopropyl groups. 28-29.(canceled)
 30. The composition according to claim 1, wherein said one ormore polar or polarising group(s) on the organic binder is independentlyselected from the group consisting of nitro group, nitrile group, C₁₋₄₀alkyl group substituted with a nitro group, a nitrile group, a cyanategroup, an isocyanate group, a thiocyanate group or a thioisocyanategroup; C₁₋₄₀ alkoxy group optionally substituted with a nitro group, anitrile group, a cyanate group, an isocyanate group, a thiocyanate groupor a thioisocyanate group; C₁₋₄₀ carboxylic acid group optionallysubstituted with a nitro group, a nitrile group, a cyanate group, anisocyanate group, a thiocyanate group or a thioisocyanate group; C₂₋₄₀carboxylic acid ester optionally substituted with a nitro group, anitrile group, a cyanate group, an isocyanate group, a thiocyanate groupor a thioisocyanate group; sulfonic acid optionally substituted with anitro group, a nitrile group, a cyanate group, an isocyanate group, athiocyanate group or a thioisocyanate group; sulfonic acid esteroptionally substituted with a nitro group, a nitrile group, a cyanategroup, an isocyanate group, a thiocyanate group or a thioisocyanategroup; cyanate group, isocyanate group, thiocyanate group,thioisocyanate group; and an amino group optionally substituted with anitro group, a nitrile group, a cyanate group, an isocyanate group, athiocyanate group or a thioisocyanate group; and combinations thereof.31. The composition according to claim 1, wherein said one or more polaror polarising group(s) is independently is selected from the groupconsisting of C₁₋₄ cyanoalkyl group, C₁₋₁₀ alkoxy group, nitrile group,amino group and combinations thereof.
 32. The composition according toclaim 1, wherein the polar or polarizing group is selected from thegroup consisting of methoxy, ethoxy, propoxy, butoxy, cyanomethyl,cyanoethyl, nitrile, NH₂ and combinations thereof.
 33. The compositionaccording to any of claim 1, wherein Ar₁, Ar₂ and Ar₃, are independentlyselected from the group consisting of C₆₋₁₀ aryl, C₇₋₁₂ aralkyl andC₇₋₁₂ alkaryl, any of which may be substituted with 1, 2, or 3 groupsindependently selected from C₁₋₂ alkoxy, C₁₋₃ cyanoalkyl, CN andmixtures thereof, and n=1 to
 10. 34. The composition according to any ofclaim 1, wherein Ar₁, Ar₂ and Ar₃ are all phenyl which may beindependently substituted with 1 or 2 groups selected from methoxy,cyanomethyl and CN and mixtures thereof, and n=1 to
 10. 35. (canceled)36. The composition according to claim 1, wherein said organic bindercomprises at least one unit selected from the following structures (G)to (J):

37-40. (canceled)
 41. The composition according to claim 1, wherein saidcomposition has a charge mobility value of at least 0.5 cm V⁻¹ s⁻¹. 42.The composition according to claim 41, wherein said composition has acharge mobility value of between 1.5 and 8.0 cm V⁻¹ s⁻¹. 43-45.(canceled)
 46. A method of forming the organic semiconductor layeraccording to claim 1, comprising the steps of: a. Mixing the organicsemiconductor composition according to the present invention with asolvent to form a semiconductor layer formulation; b. Depositing saidformulation onto a substrate; and c. Optionally removing the solvent toform an organic semiconductor layer. 47-51. (canceled)
 52. An electronicdevice comprising the organic semiconductor composition or layeraccording to any of claim
 1. 53. The electronic device according toclaim 52, wherein said device is selected from the group consisting oforganic field effect transistors (OFETS), integrated circuits, organiclight emitting diodes (OLEDS), photodetectors, organic photovoltaic(OPV) cells, sensors, lasers, memory elements and logic circuits. 54.(canceled)